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Code P1131 would indicate that there is a lack of switching for heated oxygen sensor bank 1, sensor 1, fuel trim is at the limit. According to the factory service manual, this can be caused by the following:
- 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)
Looks like you have a few items to check. If a quick check of most of these items does not reveal anything, and you are comfortable doing it, I'd suggest you get a can of SeaFoam and use it to perform a cylinder de-carbonization. Instructions are on the SeaFoam can. Maybe as the engine warms up, the carbon is becoming a sponge and absorbing the fuel. Also, if you have a fuel pressure tester (or don't mind spending $25 or less to buy one), make sure your fuel pressure isn't dropping when warm. It wouldn't be a stretch to suspect that your fuel pump may be getting weak.
-Rod
09-01-2007, 08:25 AM
Engine misses 3500 ROM
