P0169
PowertrainFuel Systemmoderate severityIncorrect Fuel Composition
What P0169 Means
The PCM has detected that the fuel composition is outside expected parameters, common in flex-fuel systems monitoring ethanol content. Incorrect composition data can cause the engine to run rich or lean.
Symptoms
- Rough running or hesitation
- Hard starting
- Check engine light on
Common Causes
- Faulty fuel composition sensor
- Wrong fuel or bad fuel in tank
- Sensor wiring or connector fault
- Contaminated or water-laden fuel
Diagnostic Steps
- Read fuel composition/ethanol sensor data with scan tool
- Verify correct fuel type is in the tank
- Inspect sensor wiring and connectors
- Test or replace fuel composition sensor if out of range
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