242
UnclassifiedGeneral
What This Code Means
System running rich; Rich exhaust condition; Sensed RPM becomes higher than actual speed; ECM delivers too much fuel; ECM registers a higher manifold pressure than normal; ECM senses too cold of incoming air; ECM senses engine temperature colder than it actually is
Possible Causes
- •Faulty HO2S sensor
- •Faulty cam position sensor causing EMI noise
- •Faulty crank position sensor causing EMI noise
- •Injector failing in an open manner
- •MAP sensor output causing higher manifold pressure registration
- •Open ground circuit to or in the ignition system or ECM causing EMI noise
- •Shifted ECT sensor
- •Shifted MAT sensor
Suggested Actions
- 1Check for a shifted ECT sensor
- 2Check for a shifted MAT sensor
- 3Disconnect the MAP sensor to allow the ECM to set a default value for MAP
- 4If all tests are OK, replace HO2S Sensor with a known good part and retest
- 5If any other DTCs are present, diagnose those first
- 6Refer to the Injector Test Mode if injector problems are suspected
- 7Substitute a known good MAP sensor if the rich condition is gone while the sensor is disconnected
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