engine help plz
- Thread starter Cociorvan
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wmburns
SN Certified Technician
Very hard to help when the full DTC codes are not posted. There are hundreds of codes that some appear to be all the same. Go back to the autoparts store to have your codes read. Update the post with the full DTC codes.
Also, what model year car are we dealing with? How many miles? What kind of mods? These things make a difference.
In the mean time, start by checking your fuses (all of them inside the engine compartment and the passenger compartment).
Next, check the electrical connection to the speed sensor on the transmission tail shaft. Is it clean and tight? Any bent or pushed pins?
OBTW, many functions on the PCM need to know the car's speed. Possible for other DTC's to be related to a speed sensor problem. Does the speedometer work? Again, the car's MY is important. For example, the speedometer works differently on an electriconic car (96+) than an older electro/mechanical car.
Also, what model year car are we dealing with? How many miles? What kind of mods? These things make a difference.
In the mean time, start by checking your fuses (all of them inside the engine compartment and the passenger compartment).
Next, check the electrical connection to the speed sensor on the transmission tail shaft. Is it clean and tight? Any bent or pushed pins?
OBTW, many functions on the PCM need to know the car's speed. Possible for other DTC's to be related to a speed sensor problem. Does the speedometer work? Again, the car's MY is important. For example, the speedometer works differently on an electriconic car (96+) than an older electro/mechanical car.
wmburns
SN Certified Technician
Below is the information from the 2002 MY. It should give you an idea of what to check. This particular O2 sensor DTC has a lot of possible causes. However, the very FIRST thing to check is for vacuum leaks.
>>from 2002 MY Ford service manual
P1131 - Lack of HO2S-11 Switch, Sensor Indicates Lean
A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time.
See Possible Causes for DTC P1130
P1130 - Lack of HO2S-11 Switch, Fuel Trim at Limit
The HEGO Sensor is monitored for switching. The test fails when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit.
Electrical:
Short to VPWR in harness or HO2S
Water in harness connector
Open/Shorted HO2S circuit
Corrosion or poor mating terminals and wiring
Damaged HO2S
Damaged PCM
Fuel System:
Excessive fuel pressure
Leaking/contaminated fuel injectors
Leaking fuel pressure regulator
Low fuel pressure or running out of fuel
Vapor recovery system
Induction System:
Air leaks after the MAF
Vacuum Leaks
PCV system
Improperly seated engine oil dipstick
EGR System:
Leaking gasket
Stuck EGR valve
Leaking diaphragm or EVR
Base Engine:
Oil overfill
Cam timing
Cylinder compression
Exhaust leaks before or near the HO2S(s)
A fuel control HO2S PID switching across 0.45 volt from 0.2 to 0.9 volt indicates a normal switching HO2S.
P0720 - Insufficient input from Output Shaft Speed sensor
The output shaft speed sensor inputs a signal to the PCM, based on the speed of the output shaft of the transmission. The PCM compares this signal with the signal of the VSS or TCSS and determines correct tire size and axle gear ratio.
OSS sensor circuit short to GND
OSS sensor circuit short to PWR
OSS sensor circuit open
Damaged OSS sensor
Damaged PCM
Verify sensor signal output varies with vehicle speed.
>>from 2002 MY Ford service manual
P1131 - Lack of HO2S-11 Switch, Sensor Indicates Lean
A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time.
See Possible Causes for DTC P1130
P1130 - Lack of HO2S-11 Switch, Fuel Trim at Limit
The HEGO Sensor is monitored for switching. The test fails when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit.
Electrical:
Short to VPWR in harness or HO2S
Water in harness connector
Open/Shorted HO2S circuit
Corrosion or poor mating terminals and wiring
Damaged HO2S
Damaged PCM
Fuel System:
Excessive fuel pressure
Leaking/contaminated fuel injectors
Leaking fuel pressure regulator
Low fuel pressure or running out of fuel
Vapor recovery system
Induction System:
Air leaks after the MAF
Vacuum Leaks
PCV system
Improperly seated engine oil dipstick
EGR System:
Leaking gasket
Stuck EGR valve
Leaking diaphragm or EVR
Base Engine:
Oil overfill
Cam timing
Cylinder compression
Exhaust leaks before or near the HO2S(s)
A fuel control HO2S PID switching across 0.45 volt from 0.2 to 0.9 volt indicates a normal switching HO2S.
P0720 - Insufficient input from Output Shaft Speed sensor
The output shaft speed sensor inputs a signal to the PCM, based on the speed of the output shaft of the transmission. The PCM compares this signal with the signal of the VSS or TCSS and determines correct tire size and axle gear ratio.
OSS sensor circuit short to GND
OSS sensor circuit short to PWR
OSS sensor circuit open
Damaged OSS sensor
Damaged PCM
Verify sensor signal output varies with vehicle speed.
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