2001 p0455 ca smog fail

po455

look in this link is for 2005 and up....go into pc/ed u will see more info..

what im getting to is in the pic of the system on ours it shows the vapor hose before the tb...than in the link its after tb....

that was my problem...vac hose was in wrong place

FYI: on-line fully browseable Service Manual - Ford Mustang Forums

I went out to look at my 2000 GT SOHC. To me, it looks hard to hook the EVAP lines up wrong.

The large EVAP lines goes to a single 1/4" port on the rear of the upper throttle body plenum. It is the ONLY thing on that port.

The smaller 1/8" lines run from a vacuum port on the front of the TB near the butterfly valve. The small lines "Y's" off going to the left side of the engine (Fuel pressure sensor and EGR vacuum transducer). On the right side, there is another "Y" fitting. One small line continues through the dash for the AC/heater damper adjusters. The other goes through the right hand fender liner onto the EVAP purge valve.

The source of the engine vacuum for the EVAP pressure test is the smaller 1/8" lines. These lines are small enough that a small leak may not cause terrible driving issues. However, a small leak may limit the amount of vacuum available to pull down the EVAP system for the test.

The OP has already confirmed vacuum at the smaller line on the EVAP purge valve.

The larger line carries the vapors during an EVAP purge. IMO, a leak on this line between the EVAP purge valve and TB would cause a noticable vacuum leak. The OP has already reported replacing these lines anyway.

There are two different operating modes of the EVAP system. The EVAP purge and the pressure test. From the DTC, we really don't know which is failing.

Although I have to admit to not fully understand how the PCM determines there is not enough flow. The older Mustangs had a EVAP flow sensor.

Of course it might be possible that the failing test is only the pressure test. I say that because the charcoal canister on my 2000 is almost totally clogged and it never throws a DTC. That tends to say if the pressure test passes, the PCM is happy.

po455

01blackvertgt said:

Yes the 1/8" lines in the engine would be hard to hook up wrong on my 01. do you mean to tell me that the way the test is done is by: closing both purge and vent valves and then pulling a vacuum thru the purge valve small line?

wow, than I really need to check the network of 1/8" hoses on my engine. I plan to swap the VMV (purge valve, since I have the extra one from the wrecking yard.) and i will make sure there is flow from and no vacuum on the 1/8" network.

next step would point to the tank pressure sensor, but that should throw a code, I think?

The Mobile mechanic had the $10K reader/programmer and we did look at the VMV voltages and vent valve voltages, we could not find the pressure sensor on his list of 30 sensors.

BTW thanks on the "sticking it out" kudos, I have always fixed my cars, this is my 6th stang, 8th ford and am in the middle of doing a frame off upgrade/restore of my 75 Bronco, 91 5.0l HO, AOD with 4RW70 internals and NP205 TC, I will do the EFI swap from the 91 stang and am using GT40P heads and intake from an explorer. I am FORD all the way, the stang passes the visual and sniffer test, it is super cool, I want to keep it and have it become classic on my watch.

Thanks for your efforts guys,

Click to expand...

only the big hose was wrong on mine...i cant seem to find the old 1/8 line,but did find the others,,,i also took out the test port line and plugged it..

as wmburns stated the po455 is a 2 part code...leak or no flow-so maybe changing the valve in fender well could change things

there are more codes on evap,,and like you said should cause a light.

the link doesnt have all the pin test...pin test HX covers some things not in the pdf i sent you..

HX is large ill post it up..hope the format stays readable.

pin test HX

2003 PCED OBD SECTION 5: Pinpoint Tests
Procedure revision date: 08/19/2002

--------------------------------------------------------------------------------
HX: Evaporative Emission (EVAP) Monitor and System HX: Introduction

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HX1 DTC P0443: INSPECT EVAP CANISTER PURGE VALVE CIRCUIT FOR INTERMITTENT FAILURE
Rerun KOEO, KOER Self-Tests and retrieve Continuous Memory DTCs.
Is DTC P0443 present in Continuous Memory Self-Test only?
Yes No
The fault that produced Continuous Memory DTC P0443 can be intermittent. GO to Z1 . If OK REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). GO to HX2 .

HX2 DTC P0443: CHECK VPWR VOLTAGE TO EVAP CANISTER PURGE VALVE
Key off.
Disconnect EVAP canister purge valve.
Key on, engine off.
Measure voltage between VPWR circuit at the EVAP canister purge valve harness connector and battery negative post.
Is voltage greater than 10.5 volts?
Yes No
For LS6/LS8/Thunderbird/2.3L Focus:

KEY OFF. GO to HX3 .

For All others:

KEY OFF. GO to HX4 REPAIR open circuit.

HX3 CHECK EVAP CANISTER PURGE VALVE RESISTANCE FOR LS6/LS8/THUNDERBIRD/2.3L FOCUS
Note: EVAP canister purge valve resistance reading must be taken with engine cooled down.

Disconnect EVAP canister purge valve.
Measure EVAP canister purge valve resistance.
Is resistance between 2.5 and 6.0 ohms?
Yes No
GO to HX5 . REPLACE damaged EVAP canister purge valve. COMPLETE an Evaporative Emission Leak Check Monitor Repair Verification Drive Cycle (REFER to Section 2, Drive Cycles ).

HX4 CHECK EVAP CANISTER PURGE VALVE RESISTANCE
Note: EVAP canister purge valve resistance reading must be taken with engine cooled down.

Disconnect EVAP canister purge valve.
Measure EVAP canister purge valve resistance.
Is resistance between 30 and 38 ohms?
Yes No
GO to HX5 . REPLACE damaged EVAP canister purge valve. COMPLETE an Evaporative Emission Leak Check Monitor Repair Verification Drive Cycle (REFER to Section 2, Drive Cycles ).

HX5 CHECK EVAP CANISTER PURGE VALVE CIRCUIT FOR OPEN IN HARNESS
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect PCM.
Measure resistance of EVAP canister purge valve circuit between PCM harness connector pin and EVAP canister purge valve harness connector.
Is resistance less than 5.0 ohms?
Yes No
GO to HX6 . REPAIR open circuit.

HX6 CHECK EVAP CANISTER PURGE VALVE CIRCUIT FOR SHORT TO PWR GND IN HARNESS
Disconnect scan tool from DLC.
Measure resistance between EVAP canister purge valve circuit at the EVAP canister purge valve harness connector and battery negative post.
Is resistance greater than 10,000 ohms?
Yes No
GO to HX7 . REPAIR short circuit.

HX7 CHECK EVAP CANISTER PURGE VALVE CIRCUIT FOR SHORT TO VPWR IN HARNESS
Key on, engine off.
Measure voltage between EVAP canister purge valve circuit at the EVAP canister purge valve harness connector and battery negative post.
Is voltage greater than 10.5 volts?
Yes No
REPAIR short circuit. REPLACE PCM. (Refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ).

HX18 DTC P1450: CHECK FOR VISUAL CAUSES OF EXCESSIVE FUEL TANK VACUUM
Note: If the EVAP canister-CV solenoid and fuel tank assemblies are not accessible during this pinpoint test step, GO to Evaporative Emissions, Section 303 in the Workshop Manual for removal instructions. For Aviator application, REFER to Section 310 in the Workshop Manual for removal instructions.

Check for kinks or bends in the fuel vapor hoses/tubes (EVAP canister purge outlet tube and EVAP canister tube).
Visually inspect EVAP canister inlet port, CV solenoid filter and canister vent hose assembly for contamination or debris.
Check CV solenoid filter for blockage or contamination.
Is a fault indicated?
Yes No
REMOVE any contamination or debris around fuel vapor hoses/tubes and EVAP canister- CV solenoid assembly. REMOVE kinks or bends in EVAP canister purge outlet tube, EVAP canister tube and canister vent hose assembly. CLEAR Continuous Memory DTCs. FOLLOW the Vehicle Preparation for Monitor Repair Verification Drive Cycle and COMPLETE an Evaporative Emission Leak Check Monitor Repair Verification Drive Cycle (REFER to Drive Cycles ). RETRIEVE Continuous Memory DTCs. If DTC 1450 is still present, GO to HX19 . GO to HX19 .

HX19 CHECK FUEL TANK PRESSURE SENSOR VOLTAGE
Connect scan tool.
Key on, engine off.
Access FTP V PID.
Is the FTP V PID between 2.40 to 2.80 volts with the fuel filler cap on?
Yes No
A possible intermittent condition on the FTP sensor circuit can cause the DTC P1450. GO to Z1 . If circuit is OK, REFER to Evaporative Emissions, Section 303 (for Aviator, REFER to Section 310), Diagnostic Trouble Code/Symptom Chart in the Workshop Manual for a blocked (plugged) EVAP system condition. KEY OFF. GO to HX20 .

HX20 CHECK FUEL TANK PRESSURE SENSOR VOLTAGE WITH FUEL FILLER CAP REMOVED
Remove the fuel filler cap.
Key on, engine off.
Access FTP V PID.
Is the FTP V PID between 2.40 to 2.80 volts with fuel filler cap off?
Yes No
REFER to Evaporative Emissions, Section 303 (for Aviator, REFER to Section 310), in the Workshop Manual for a blocked (plugged) EVAP system condition. KEY OFF. GO to HX21 .

HX21 CHECK FOR OTHER DTCS PRESENT
Check for other three wire sensor DTCs (KOEO, KOER or Continuous Memory) present with the DTC P1450.
Are other DTCs present?
Yes No
RETURN to Diagnostic Subroutines, Section 4 , for direction in addressing the other DTCs. KEY OFF. GO to HX22 .

HX22 CHECK VREF FROM PCM TO FTP SENSOR
Disconnect FTP sensor.
Key on, engine off.
Measure voltage between VREF and SIG RTN circuits at the FTP sensor harness connector.
Is voltage between 4.0 and 6.0 volts?
Yes No
KEY OFF. REPLACE damaged FTP sensor. CLEAR Continuous Memory DTCs. FOLLOW the Vehicle Preparation for Monitor Repair Verification Drive Cycle and COMPLETE an Evaporative Emission Leak Check Monitor Repair Verification Drive Cycle (REFER to Section 2, Drive Cycles ). RETRIEVE Continuous Memory DTCs. If DTC P1450 is still present, REFER to Evaporative Emissions, Section 303 (for Aviator, REFER to Section 310), Diagnostic Trouble Code/Symptom Chart, in the Workshop Manual. KEY OFF. GO to HX23 .

HX23 CHECK FOR OPEN VREF AND SIG RTN CIRCUITS BETWEEN PCM AND FTP SENSOR
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect PCM.
Measure resistance of VREF circuit between PCM harness connector pin and FTP sensor harness connector.
Measure resistance of SIG RTN circuit between PCM harness connector pin and FTP sensor harness connector.
Is each resistance less than 5.0 ohms?
Yes No
REPLACE PCM (REFER to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). REPAIR open circuit.

HX26 DTC P0452: CHECK FOR FTP SENSOR CONNECTOR CONTAMINATION
Key off.
Visually check for liquid fuel contamination of the FTP sensor electrical connector.
Check for completely submerged FTP sensor (tank mounted type only) in liquid fuel (can affect correct FTP voltage reading).
Does FTP sensor and its electrical connector show signs of fuel contamination?
Yes No
REPAIR FTP sensor electrical connector as necessary. ADJUST fuel tank overfill. GO to HX27 .

HX27 CHECK FOR LOW FTP SENSOR VOLTAGE
Note: FTP sensor input with no pressure/vacuum on the fuel tank (filler cap open or not open to atmosphere) is between 2.37 and 2.97 volts.

Connect scan tool.
Key on, engine off.
Access FTP V PID.
If FTP V PID is not present on the scan tool, measure voltage between FTP and SIG RTN circuits at the PCM harness connector with PCM connected.
Is measured voltage or FTP V PID reading less than 0.22 volt?
Yes No
KEY OFF. GO to HX28 . The fault that produced the DTC P0452 is intermittent. GO to Z1 .

HX28 CHECK OPPOSITE INDUCED HIGH FTP SIGNAL
Disconnect FTP sensor.
Connect a jumper wire between VREF circuit and FTP circuits at the FTP sensor harness connector.
Key on, engine off.
Measure voltage between FTP circuit at the FTP sensor harness connector and chassis ground.
Is measured voltage reading between 4.0 and 6.0 volts?
Yes No
REPLACE FTP sensor. REFER to Evaporative Emissions, Section 303 (for Aviator, REFER to Section 310) in the Workshop Manual for component removal and installation. RESTORE vehicle. FOLLOW the Vehicle Preparation for Monitor Repair Verification Drive Cycle and COMPLETE an Evaporative Emission Leak Check Monitor Repair Verification Drive Cycle (REFER to Section 2, Drive Cycles ). REMOVE jumper. GO to HX29 .

HX29 CHECK VOLTAGE BETWEEN VREF AND SIG RTN CIRCUITS AT FTP SENSOR
Key on, engine off.
Measure voltage between VREF and SIG RTN circuits at the FTP sensor harness connector.
Is voltage between 4.0 and 6.0 volts?
Yes No
KEY OFF. GO to HX30 . VREF voltage is out of range. GO to C1 .

HX30 CHECK FTP CIRCUIT FOR SHORT TO SIG RTN OR PWR GND IN HARNESS
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect PCM.
Disconnect scan tool from DLC.
Measure resistance between FTP and SIG RTN circuits at the PCM harness connector.
Measure resistance between FTP circuit at the PCM harness connector and battery negative post.
Is each resistance greater than 10,000 ohms?
Yes No
REPLACE PCM (REFER to Section 2, Drive Cycles ). REPAIR short circuit.

HX33 DTC P0453: CHECK FOR HIGH FTP SENSOR VOLTAGE
Note: FTP sensor input with no pressure/vacuum on the fuel tank (fuel filler cap open or not open to atmosphere) is 2.37 to 2.97 volts.

Connect scan tool.
Key on, engine off.
Access FTP V PID.
If FTP V PID is not present on the scan tool, measure voltage between FTP and SIG RTN circuits at the PCM harness connector with PCM connected.
Is measured voltage or FTP V PID reading greater than 4.50 volts?
Yes No
KEY OFF. GO to HX34 . The fault that produced DTC P0453 is intermittent. GO to Z1 .

HX34 CHECK FTP CIRCUIT FOR SHORT TO POWER
Disconnect FTP sensor.
Key on, engine off.
Measure voltage between FTP circuit at the FTP sensor harness connector and battery negative post.
Is the voltage greater than 10.5 volts?
Yes No
KEY OFF. The FTP is indicating a short to VPWR. GO to HX35 . KEY OFF. GO to HX36 .

HX35 CHECK FTP CIRCUIT FOR SHORT TO VPWR IN HARNESS
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect PCM.
Key on, engine off.
Measure the voltage between FTP circuit at the PCM harness connector and battery negative post.
Is voltage greater than 10.5 volts?
Yes No
REPAIR short circuit. REPLACE PCM. (REFER to Section 2 , Flash EEPROM.)

HX36 CHECK OPPOSITE INDUCED LOW FTP SIGNAL
Connect a jumper wire between SIG RTN and FTP circuits at the FTP sensor harness connector.
Key on, engine off.
If a scan tool communication concern exists, turn the key off, remove jumper immediately and GO to HX41 .
Access FTP V PID.
If FTP V PID is not present on the scan tool, measure voltage between FTP and SIG RTN circuits at the PCM harness connector with PCM connected.
Is measured voltage or FTP V PID reading less than 0.10 volt?
Yes No
REMOVE jumper. GO to HX37 . Unable to induce opposite signal. KEY OFF. GO to HX39 .

HX37 CHECK FOR IN RANGE VOLTAGE BETWEEN VREF AND SIG RTN CIRCUITS AT FTP SENSOR
Key on, engine off.
Measure voltage between VREF and SIG RTN circuits at the FTP sensor vehicle harness connector.
Is voltage between 4.0 and 6.0 volts?
Yes No
KEY OFF. GO to HX38 . VREF voltage is out of range. GO to C1 .

HX38 CHECK FTP CIRCUIT FOR SHORT TO VREF IN SENSOR OR HARNESS
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect PCM.
Measure resistance between FTP and VREF circuits at the PCM harness connector. (For 150 PIN PCM, measure to both VREF pins.)
Is the resistance greater than 10,000 ohms?
Yes No
REPLACE FTP sensor. REFER to Evaporative Emissions, Section 303 (for Aviator, REFER to Section 310), in the Workshop Manual for component removal and installation. RESTORE vehicle. FOLLOW the Vehicle Preparation for Monitor Repair Verification Drive Cycle and COMPLETE an Evaporative Emission Leak Check Monitor Repair Verification Drive Cycle (REFER to Section 2, Drive Cycles ). REPAIR short circuit.

HX39 CHECK FTP CIRCUIT FOR OPEN IN HARNESS
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect PCM.
Measure resistance of FTP circuit between PCM harness connector pin and FTP sensor harness connector.
Is resistance less than 5.0 ohms?
Yes No
GO to HX40 . REPAIR open circuit.

HX40 CHECK FOR OPEN SIG RTN CIRCUIT BETWEEN PCM AND FTP SENSOR
Measure resistance of SIG RTN circuit between PCM harness connector pin and FTP sensor harness connector.
Is resistance less than 5.0 ohms?
Yes No
GO to HX41 . REPAIR open circuit.

HX41 CHECK FTP CIRCUIT FOR SHORT TO VREF IN PCM
PCM disconnected.
Measure resistance between FTP and VREF circuits at the PCM harness connector. (For 150 PIN PCM, measure to both VREF pins.)
Is the resistance greater than 10,000 ohms?
Yes No
REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). REPAIR short circuit.

HX43 DTC P0457: CHECK FOR MISSING OR LEAKING FUEL FILLER CAP
Check for missing fuel filler cap.
Check for a loose fuel filler cap.
Check for possible cross-thread fuel filler cap condition.
Is a concern present with the proper installation of the fuel filler cap?
Yes No
REPLACE cross-threaded or damaged fuel filler cap. RECONNECT and TIGHTEN the fuel filler cap only one-eighth turn so that the cap initially clicks by sound or touch. COMPLETE PCM KAM Reset to clear DTCs and adaptive memory. (REFER to Section 2, Diagnostic Methods ). COMPLETE an Evaporative Emission Leak Check Monitor Repair Verification Drive Cycle (REFER to Section 2, Drive Cycles ). RERUN Quick Test. If DTC P0455 is present, REFER to Evaporative Emissions, Section 303 (for Aviator, REFER to Section 310), Diagnostic Trouble Code/Symptom Chart in the Workshop Manual. COMPLETE PCM KAM Reset to clear DTCs and adaptive memory. (REFER to Section 2, Diagnostic Methods ). COMPLETE an Evaporative Emission Leak Check Monitor Repair Verification Drive Cycle (REFER to Section 2, Drive Cycles ). RERUN Quick Test. If DTC P0455 is present, REFER to Evaporative Emissions, Section 303 (for Aviator, REFER to Section 310), Diagnostic Trouble Code/Symptom Chart in the Workshop Manual. Otherwise, INFORM the vehicle owner that it is important and necessary to immediately install the fuel filler cap after every refueling event.

HX65 DTC P1451 OR P0446: CHECK VPWR VOLTAGE TO CV SOLENOID
Key off.
Disconnect canister vent (CV) solenoid.
Connect a non-powered test lamp between CV and VPWR circuits at the CV solenoid harness connector.
Key on, engine off.
Attempt to close and open CV solenoid driver in PCM by accessing Output Test Mode.
Select ALL OFF mode.
Cycle START button ON and OFF, and observe the test lamp.
Does the test lamp cycle on and off (light up and turn off)?
Yes No
KEY OFF. GO to HX66 . For test lamp always off :

GO to HX67 .

For test lamp always on :

KEY OFF. GO to HX70 .

HX66 CHECK CV SOLENOID RESISTANCE
Measure CV solenoid resistance.
Is resistance between 48 and 65 ohms?
Yes No
Unable to identify fault at this time. GO to Z1 . REPLACE damaged CV solenoid. COMPLETE an EVAP system leak test at the evaporative test port to VERIFY that a leak did not occur during component replacement. FOLLOW the Vehicle Preparation for Monitor Repair Verification Drive Cycle and COMPLETE an Evaporative Emission Leak Check Monitor Repair Verification Drive Cycle (REFER to Section 2, Drive Cycles ).

HX67 CHECK FOR OPEN VPWR CIRCUIT BETWEEN CV SOLENOID AND POWER RELAY
Measure voltage between VPWR circuit at the CV solenoid harness connector and battery negative post.
Is voltage greater than 10.5 volts?
Yes No
KEY OFF. GO to HX68 . KEY OFF. REPAIR open circuit.

HX68 CHECK VPWR CIRCUIT FOR OPEN IN HARNESS
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect PCM.
Measure resistance of VPWR circuit between PCM harness connector pin (or for 150 PIN PCM, the VPWR fuse to the power relay) and CV solenoid harness connector.
Is resistance less than 5.0 ohms?
Yes No
GO to HX69 . REPAIR open circuit.

HX69 CHECK CV CIRCUIT FOR OPEN IN HARNESS
Measure resistance of CV circuit between PCM harness connector pin and CV solenoid harness connector.
Is resistance less than 5.0 ohms?
Yes No
KEY OFF. REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). REPAIR open circuit.

HX70 CHECK CV CIRCUIT FOR SHORT TO PWR GND IN HARNESS
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect PCM.
Disconnect scan tool from DLC.
Measure resistance between CV circuit at the CV solenoid harness connector and battery negative post.
Is resistance greater than 10,000 ohms?
Yes No
RECONNECT scan tool. GO to HX71 . REPAIR short circuit.

HX71 CHECK CV CIRCUIT FOR SHORT TO PWR OR CHASSIS GND IN HARNESS
Key on, engine off.
Measure voltage between CV circuit at the PCM harness connector and chassis ground.
Is voltage less than 1.0 volt?
Yes No
KEY OFF. REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). KEY OFF. REPAIR short circuit to VPWR, VREF or chassis ground.

HX76 DTC P0460, P0462 OR P0463: CHECK FUEL TANK LEVEL VOLTAGE RANGE
Note: For Focus, Escape, Mustang, LS6/LS8, Thunderbird, Town Car, Windstar, Explorer/Mountaineer, Aviator, 4.6L/5.4L E-Series, F-Series, Expedition/Navigator/Blackwood and Excursion applications, do not continue with step HX76. Instead, go to Instrument Cluster Section 413, fuel level indicator or Rear Electronic Module (REM) diagnosis in the Workshop Manual.

Key on, engine running.
Access fuel level input voltage (FLI) PID.
Is the fuel level input voltage (FLI) PID reading between .25 and 4.5 volts?
Yes No
GO to HX77 . GO to HX80 .

HX77 CHECK FOR FUEL TANK FLOAT LEVEL RESPONSE
Key on, engine off.
Observe the FLI PID.
If fuel level is under one quarter (25% on FLI PID), add fuel (7.57 to 11.36 liters [2 to 3 gallons]) to the fuel tank.
If fuel level is greater than three quarters (75% on FLI PID), drain (7.57 to 11.36 liters [2 to 3 gallons]) fuel from the fuel tank.
Did the FLI PID indicate a movement upward or downward as fuel is either added or drained?
Yes No
No concern found at this time. GO to Z1 for possible intermittent condition. (Frequent filling of the fuel tank without allowing fuel level to drop below the full mark may contribute to a P0460 DTC.) KEY OFF. REFER to Instrument Cluster Section 413 in the Workshop Manual for inoperative fuel level sender.

HX80 CHECK FLI CIRCUIT VOLTAGE AT FP MODULE
Disconnect the instrument cluster connector to the fuel gauge. (Refer to Instrument Cluster Section 413 in the Workshop Manual or Wiring Diagram manual for cluster connector configuration.)
Key on, engine off.
Measure voltage between FLI circuit at the FP module harness connector and battery negative post.
Is voltage greater than 5 volts?
Yes No
KEY OFF. GO to HX81 . KEY OFF. GO to HX82 .

HX81 CHECK FLI CIRCUIT FOR SHORT TO VPWR IN HARNESS
Disconnect PCM.
Key on, engine off.
Measure voltage between FLI circuit at the FP module harness connector and battery negative post.
Is voltage greater than 10.5 volts?
Yes No
REPAIR short circuit. REPLACE PCM (REFER to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ).

HX82 CHECK FLI CIRCUIT FOR SHORT TO PWR GND IN HARNESS
Disconnect PCM.
Measure resistance between FLI circuit at the PCM harness connector and battery negative post.
Is resistance greater than 10,000 ohms?
Yes No
GO to HX83 . REPAIR short circuit.

HX83 CHECK FLI CIRCUIT FOR SHORT TO CASE GND IN HARNESS
Measure resistance between FLI and CASE GND circuits at the PCM harness connector.
Is resistance greater than 10,000 ohms?
Yes No
GO to HX85 . REPAIR short between FLI and CASE GND circuits.

HX85 CHECK FLI CIRCUIT FOR OPEN IN HARNESS
Measure resistance of FLI circuit between PCM harness connector and fuel pump (FP) module (pigtail) harness connector.
Measure resistance of FLI circuit between PCM harness connector and the instrument cluster fuel gauge harness connector.
Is each resistance less than 10.0 ohms?
Yes No
GO to HX86 . REPAIR open circuit.

HX86 CHECK CASE GND CIRCUIT FOR OPEN IN HARNESS
Measure resistance of CASE GND circuit between PCM harness connector and FP module (pigtail) harness connector.
Measure resistance between the CASE GND circuit at the PCM harness connector and the fuel gauge ground at the instrument cluster fuel gauge harness connector.
Is each resistance less than 10.0 ohms?
Yes No
REFER to Instrument Cluster Section 413 in the Workshop Manual (reference: Wiring Diagram manual) for fuel gauge diagnosis. REPLACE fuel gauge or REPAIR as necessary. Then RERUN Quick Test. If DTC P0460, P0462 or P0463 are still present, REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). REPAIR open circuit.

HX88 CHECK FUEL CAP LAMP ALWAYS ON W/O DTCS
Disconnect PCM.
Key on, engine off.
Is the Check Fuel Cap Indicator Lamp OFF with the PCM disconnected?
Yes No
KEY OFF. REPLACE PCM (REFER to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). The PCM has not attempted to ground the circuit between the Check Fuel Cap Indicator Lamp and corresponding PCM pin. This has not turned the indicator lamp ON. REFER to Instrument Cluster Section 413 in the Workshop Manual.

HX89 CHECK FUEL CAP LAMP ALWAYS OFF W/O DTCS
Key off.
Disconnect the Check Fuel Cap Indicator Lamp harness connector at the instrument cluster.
Disconnect PCM.
Measure resistance between PCM harness connector pin (refer to Fuel Cap Off Indicator Lamp PCM Pin Table at the beginning of this pinpoint test for correct pin number) and Check Fuel Cap circuit at the indicator lamp harness connector.
Is resistance less than 5.0 ohms?
Yes No
REFER to Instrument Cluster Section 413 in the Workshop Manual to diagnose instrument cluster and Check Fuel Cap Bulb. If OK, REPLACE PCM (REFER to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). VERIFY repair by turning key to ON position (lamp will turn OFF in 3 seconds). REPAIR open circuit. VERIFY repair by turning key to ON position (lamp will turn OFF in 3 seconds).




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01blackvertgt said:

next step would point to the tank pressure sensor, but that should throw a code, I think?

Click to expand...

Been sleeping have we? What was one of the many causes listed umpteen posts ago? Check out post #10 last item in this thread

A mechanically inoperative fuel tank pressure (FTP) sensor will throw a P0455 code. What do you have?

OBTW, there is a difference between a sensor that gives wrong readings (or the same reading all of the time) verses an electronically totally failed sensor. A disconnected or totally failed sensor will throw a specific DTC. However, if the sensor is still sending a return signal that is just plain wrong, as long as it falls within pre-established max/min values ("Martian" checks) , how is the PCM going to know?

Check out #4 under the theory of operation.

>>
4. If the initial target vacuum cannot be reached, DTC P0455 (gross leak detected) will be set. The EVAP Leak Check Monitor will abort and not continue with the leak check portion of the test.
<<

To me that says during the leak test, that the PCM attempts to pull the vapor system down to a target level and that level is NEVER reached.

The small leak DTC (P0456) means that initial vacuum was reached but not maintained for the expected length of time.

FWIIW, going back and reviewing the EVAP theory of operation, I believe that the small vacuum lines to the EVAP purge line is open to engine vacuum all of the time. Because the line is so small, this does not create any drivability issues (suspect the amount of air drawn in this way is accounted for in the tune) As the PCM increases the duty cycle from 0%, more flow is directed through the larger vacuum line.

Vacuum is created by closing the CV vent solenoid and allowing the EVAP purge valve to remain open. The FTP sensor is monitored for the target vacuum to have been reached.

The P0455 means the target vacuum was never reached. No further parts of the leak tests are run.

The sequence of events is actually very complicated. They are described in great detail in the Ford service CD. Consider getting one for yourself. They can be purchased off of ebay for usually less than $25. Well worth the $$. Tons of information.

So....you would drop the tank and install a new FTP sensor instead of testing first?

Don't you have an SCT? Why not use it to data log the FTP output? It is reasonable to assume if its value changes, the sensor is working. Just data log over a trip.

If time is important, it seems to me that you have enough knowledge to force the EVAP purge valve to open thereby pulling a vacuum on the tank. This would show up as a change in the FTP sensor's output.

Other option is to open the gas cap and see if the FTP sensor changes while monitoring with the SCT.

Consider that a 2001 is 10 years old. Gas vapors are hard on parts. I personally would never install a salvage yard FTP sensor on my car. Why? Because of the amount of work required to access the tank.

Also, I have doubts any salvage yard is going to sell just the FTP sensor. Why? Because to sell just the sensor would ruin the tank assembly. They would want you to buy the entire tank.

Using salvage yard parts elsewhere is not as much of an issue because access isn't so bad. Of course, I would still attempt to do a basic function test on any electrical part bought from a salvage yard.

Speaking from personal experience here. One of the hardest problems I ever worked on was set in motion by buying bad parts from a salvage yard. In my case, there were multiple failed parts thus making trouble shooting that much harder.

You will never guess what the problem was. No EVAP flow on a 1996 MY Mustang. Bad purge sensor as well as a bad flow solenoid.

Further, if this was me and I was prepared to drop the tank, then I would be prepared to test the other valves also installed on top of the tank. Or at the very least, check the function.

Of course one very positive of dropping the tank is the ability to perform a through inspection of the hoses, fitting, filler neck, and grommet. Inspections that is otherwise difficult to do.

At some level, you have thrown so many parts at this it would have been cheaper to let a professional fix it.

po455

i looked in the tsb 03-20-3

i was looking for more on the rubber gromet for the fuel filler neck to fuel tank..

being the code went from 455 to 457 than back to 455 the grommet rung a bell

as we are unaware on how the pcm can tell...just a thought

The OP swears that the filler neck to tank grommet is NEW. This was one of the first things mentioned. Along with checking the filler neck for rust out.

However, I did find this note in the TSB instructions.

>>
WARNING DO NOT REMOVE THE SCHRADER VALVE. REMOVING THE SCHRADER VALVE FROM THE TEST PORT ON VEHICLES EQUIPPED WITH THE ELECTRONIC VAPOR MANAGEMENT VALVE (9G641) AND/OR ELECTRONIC VAPOR MANAGEMENT VALVE & BRACKET ASSEMBLY (9G683) (SEE FIGURE 3), OR EVAP CANISTER PURGE VALVE (9C915) AND/OR EVAP CANISTER PURGE VALVE & BRACKET ASSEMBLY (9F933) (SEE FIGURE 2) WILL PERMANENTLY DAMAGE THE VALVE.
<<

The OP did report replacing the EVAP vacuum lines including the test port. Could a damaged test port Schrader valve be the source of the leak?

Seems like it should be easy to test for. The test port is not needed for operation of the car. Remove the test port and plug EVAP purge port with a suitable plug.

The PCM can tell the difference as one DTC says "the leak was so big that vacuum was never reached". Whereas the other code says, the leak was big enough such that vacuum was not held for the required length of time.

Also found this note in the TSB. It gives the voltage range for the FTP sensor output.

>>
11. The nominal value for the FTPV PID is 2.6V. If the value is greater than 2.8V or less than 2.4V, the FTP sensor is out of range and should be replaced. Verify the repair by checking to see if the new sensor is in range. For all except Windstar, LS, Thunderbird & PZEV Focus - if the sensor is within range, the concern is no longer present. (Windstar, LS, Thunderbird & PZEV Focus go to Step 12).
<<

Me I would call Ford and ask how much a new FTP sensor is. Until you check, you will never know.

FWIIW, the gas tank vapor lines were changed between 1999-2000 and 2001+. So the arrangement of lines, valves, and vent lines will be different if crossing this MY boundary.

The V6 and V8 will be the same.

Also note, if you pull a filler neck from a wreck and don't cut out the grommet first, you will damage the filler neck check value. That check valve is part of the EVAP system. It is part of the system that prevents liquid gas from getting into the venting/EVAP recovery system.

Of course it is possible this is how liquid gas got into the charcoal canister in the first place. IE the person doing the original grommet repair damaged the check valve during the repair.

Also consider that the hard plastic vent lines are heat shrunk onto the barbed fittings. Replacing the FTP sensor may be a bigger deal than you think.

The FTP sensor can be tested for at the round electrical connector near the gas tank (center below bumper). The FTP wire colors are GY/RD, RD/PK, and BN/WH. Test between the RD/PK and BN/WH.

part

google your part number...here is motorcraft part for 01

01 2001 Ford Mustang Purge Valve - Air Intake - Motorcraft - PartsGeek


i do believe most parts stores carry these

A missing or damage filler neck check valve will not throw a DTC code. It main purpose is to prevent a fuel spill in the event of a roll over. It's secondary purpose is to cut off the flow of fuel during re-filling. This is to ensure the tank is not over filled (leaving expansion room at the top and keeping liquid gas out of the vapor system).

When I replaced my filler neck and grommet, it was easy to insert the filler neck into the new tank grommet. But then again, I lubbed the grommet with petroleum jelly first.

FWIIW, the filler neck check valve is most often damaged upon removal. Most of the time because the old grommet is not completely removed first.

Since you recently dropped the tank, this also means that many vapor lines had to be disconnected. Did you have any problems removing any? Were any difficult to re-connect? Did you use your hands to disconnect or a tool?

There's a vapor line near the front center of the tank. Did you remember to re-connect?

Recommend that if doing the job again, check all fittings to ensure the O-rings are still in place inside the female fittings. Consider lubbing the male fittings with petroleum jelly before re-assembly to promote a better seal.

Consider removing the vapor lines at the charcoal canister and confirm they can be easily blown through.