p0443/p1451/p0135/p0155

Mike97gt

it doe snot
Founding Member
Jan 26, 1999
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I saw a post today where you were quoting error codes from somewhere, do you happen to have anything or know anything about a PO443 or P1451? These are Evac codes for the purge control valve, and vent solenoid on my 00 GT. I have replaced both of these items hoping to clear it up but its still throwing the same codes from when the old parts were on. Any help would be appreciated. I also have 2 more minor codes, P0135 and P0155 which is front O2 sensor heater warnings, any quick fix on this or just replace the sensors? Thanks again.

From now on when I am helping somebody in PM's with a diag I am going to post it on here. In fact I rather have them start a thread then PM me to look at it.

the reason I rather have it posted is so other members in the future can search it if they have a similar problem.
 
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Ok what I see here is circuit faults on 4 different components. I think it's extremely unlikely that all those parts went bad at once. I looked at the wirring diagram and I found a few things in common

both of the 02 sensor heater circuits and the purge and vent valve share fuse #8 in the centeral juntion box ( the box under the dash NOT UNDER THE HOOD) this fuse is a 20a fuse

another thing in common is splice #s117 this splice is near where the connector for the evap canister purge valve connector wiring comes off the main harness.

first check that fuse then get back to me.

P0443


Quote:
P0443 - EVAP Control System Canister Purge Valve Circuit Malfunction The PCM monitors the state of the EVAP canister purge valve circuit output driver. The test fails when the signal moves outside the minimum or maximum limit for the commanded state. VPWR circuit open
EVAP canister purge valve circuit shorted to GND
Damaged EVAP canister purge valve
EVAP canister purge valve circuit open
EVAP canister purge valve circuit shorted to VPWR
Damaged PCM
To verify normal function, monitor the EVAP canister purge valve signal PID EVAPPDC (or EVMV for electronic valve) and the signal voltage (PCM control side). With the valve closed, EVAPPDC will indicate 0% duty cycle (0 mA for EVMV) and the voltage approximately equal to battery voltage. When the valve is commanded fully open, EVAPPDC will indicate 100% duty cycle (1000 mA for EVMV) and a voltage drop of 3 volts minimum is normal. Output test mode may be used to switch output ON/OFF to verify function.


p1453


Quote:
P1451 - EVAP Control System Canister Vent Solenoid Circuit Malfunction Monitors the canister vent (CV) solenoid circuit for an electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified canister vent duty cycle by PCM command. VPWR circuit open
CV solenoid circuit shorted to PWR GND or CHASSIS GND
Damaged CV solenoid
CV solenoid circuit open
CV solenoid circuit shorted to VPWR
Damaged PCM
To verify normal function, monitor the EVAP canister vent solenoid signal PID EVAPCV and the signal voltage (PCM control side). With the valve open, EVAPCV will indicate 0% duty cycle and the voltage approximately equal to battery voltage. When the valve is commanded fully closed, EVAPCV will indicate 100% duty cycle and a voltage drop of 4 volts minimum is normal. Output test mode may be used to switch output ON/OFF to verify function.


p0135


Quote:
P0135 - HO2S Sensor Circuit Malfunction (HO2S-11) During testing the HO2S Heaters are checked for opens/shorts and excessive current draw. The test fails when current draw exceeds a calibrated limit and/or an open or short is detected. Short to VPWR in harness or HO2S.
Water in harness connector.
Open VPWR circuit.
Open GND circuit.
Low battery voltage.
Corrosion or poor mating terminals and wiring
Damaged HO2S heater.
Damaged PCM.
wiring.
Damaged HO2S heater.
Damaged PCM.



po155


Quote:
P0155 - HO2S Sensor Circuit Malfunction (HO2S-21) See DTC P0135
 
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This fixed the problem, i looked in the manual and it said fuses 2 and 8 both 20 amp mini fuses were "engine controls" and fuse number 8 was blown, reset the codes and no SES light!!! Check this fuse before you buy parts you dont need like i did, thanks again SVTTECH76
 
:hail2: i had this same problem that i just figured out last weekend. the fust looked fine from the top so i didnt think it was blown, pulled it out and sure enough.. replaced it and no more codes. only wish this thread was posted earlier
 
Thank you so much svttech76:hail2: I am glad I stumbled on this. Long story short, I put an x-pipe on a month ago with mil eliminators. Drove fine for about a week, no mil. On a trip my alternator died. Replaced that and my car has had a light and ran rich ever since. Got the codes pulled ended up being the p0443 and some o2 codes. Well I just checked the #8 fuse and its popped. I have been getting bad mileage ever since the mil came on down to 18 from the 24mpg that I was getting. Doing a little research about o2 heater circuits and loops I came across this. It looks like when the o2 does not heat up(because of the bad fuse) it stays in the open loop mode. Which is what it is in when you first start the car. Because of this you throw codes and run rich. Heres a little more info on the loops>
The computer uses the oxygen sensor input to regulate the fuel mixture, which is referred to as the fuel "feedback control loop." The computer takes its cues from the O2 sensor and responds by changing the fuel mixture. This produces a corresponding change in the O2 sensor reading. This is referred to as "closed loop" operation because the computer is using the O2 sensor's input to regulate the fuel mixture. The result is a constant flip-flop back and forth from rich to lean which allows the catalytic converter to operate at peak efficiency while keeping the average overall fuel mixture in proper balance to minimize emissions. It is a complicated setup but it works.

When no signal is received from the O2 sensor, as is the case when a cold engine is first started (or the 02 sensor fails), the computer orders a fixed (unchanging) rich fuel mixture. This is referred to as "open loop" operation because no input is used from the O2 sensor to regulate the fuel mixture.

If the engine fails to go into closed loop when the O2 sensor reaches operating temperature, or drops out of closed loop because the O2 sensor signal is lost, the engine will run too rich causing an increase in fuel consumption and emissions. A bad coolant sensor can also prevent the system from going into closed loop because the computer also considers engine coolant temperature when deciding whether or not to go into closed loop.
Once again thanks!
 
Sorry for bumping an old thread BUT DAMN THAT FUSE #8! CEL came on, took it to Autozone, dude said I had 8 codes!, luckily I only spent 20 on one sensor, taking it back after im done typing this. BUT im wondering what could have made the fuse blow?
 
Damn...... Thanks svttech76.......I wish I had found this thread two years ago, I have been stressin bout the emissions test. couldn't figure out the problem, and was spending alot of money tryin, who'd a thunk it... a damn fuse.. thanks a million man.
 
p0443/p1451/p0135/p0155 and fuse #8 blown

hi, i saw the post about the codes but i cant fix the problem, i put a 06 crown Vic engine in my mustang gt 2001, everything works good but the fuse #8 steel brown, i changed but it blown again, what can i do? thanks.
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If the fuse still blows, there is still a fault (short) in the circuit. Pinched or chaffed wire or something similar.

Do you have long tube headers? A common place for this to happen is where the wiring harness touches the hot headers. The insulation on the wires melts and shorts out the VPWR buss of the O2 heater circuit.

Try this, with the key off, disconnect the TPS. Measure the resistance between the GR/RD wire (1999-2004) and a known good ground. Post the results.

If the resistance is low, this indicates a short in the wiring harness. Find the short, solve the problem.

Another option is disconnect the O2 sensors. Reconnect one at a time until the fuse blows.

1999-2004 MY fuse panel schedule:
 
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I signed up just to give thanks! I have an 03 Expedition with obd2 codes: p0443/p1451/p0135/p0155 and it was fuse 33 20A. Fuse Description: (Canister vent solenoid, EVR CC, HEGO's, VMV solenoid, IMTV solenoid, AC clutch relay clutch coil.)
Again big thanks!!!
 
Hi, I thought that I had the same problem that was listed above about fuse #8 being blown, and I did so I put in a new fuse and it popped again after about 3 miles of driving. I was told I a grounding out short and I can’t seem to find it or where to really look for it. I know this thread is old but I was curious if anyone was able to help me out where to look to fix it?
 
If you are looking for an "educated guess", then look at WHAT is on the circuit in question. For the 1999-2004 model year fuse F2.8 powers the O2 heater circuits. Plus parts of the EVAP system.

If you are still looking for an "educated guess", look at the wiring to the O2 sensors. Especially the REAR O2 sensors. What will happen during exhaust work is the wiring will touch the hot exhaust. Burn though the insulation. Resulting in a short.

In general. Disconnect everything on the circuit. Plug things back in one at a time until the fuse blows. This was mentioned in the previous replies.

Still looking for an educated guess? Does this problem mainly occur after an overnight "cold soak"? What's one thing that happens a few minutes after re-staring after an over night cold soak? How about an EVAP purge? Try disconnecting the two solenoids that run the EVAP system and see what happens.

Or better yet, measure the coil resistance of the solenoids looking for an abnormally low value.

Or use an ODB2 scanner and try to see what the PCM is turning on when the fuse blows. Sometimes you can get lucky. Sometimes tracking down a short can be some of the most challenging electrical work there is. Hint. Don't take short cuts with a through visual inspection. It's amazing just how many electrical problems can be solved just for looking for hard contact points on a wiring harness.

ForScan ODB2 scanner w ELM327 USB

With an ODB2 scanner with bi-directional controls, sometimes you can "command" the PCM to turn on various solenoids. This offers an easy way to rule in or out a particular solenoid. The process of elimination is your friend. She can be a nasty one sometimes.
 
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