P1177
The ECU has run out of range in adapting the mixture in reference to the O2 Sensor signal (multiplicative adaptation) and/or in reference to the engine running conditions (additive adaptation).
Possible causes:
- Engine Temperature sensor/circuit defective, but the signal still in realistic range.
- Fuel Pressure incorrect
- Fuel Injector(s) leaking
- Fuel Injectors clogged
- Incomplete combustion (ignition or compression problem, excess O2 in the exhaust)
- Vacuum leak (lean mixture)
- Oxygen Sensor defective or contaminated with silica (Voltage change extremely slow)
- Exhaust system leak upstream of the O2 Sensor (stray air brings extra O2 making the mixture to appear lean)
- Fuel Evaporation Control system defective
- vehicle driven out of fuel (tank empty)