Engine Check - PCN?
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
Engine Check - PCN?
P1131, P1151 - 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.
Possible causes:
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 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.
Possible causes:
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)
My truck must be really messed up!
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
Engine Check - PCN?
Whatever the problem was it seems to be going away if it takes longer for the light to come back on. It wont hurt anything to keep resetting the PCM but it would be nice to know what caused the problem in the first place.
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