[amidgeha]

Post Catalyst Fuel Trim System Too Lean

The Powertrain Control Module (PCM) monitors the correction value from downstream Heated Oxygen Sensor(HO2S) as part of the fore-aft oxygen sensor control routine. The test fails when correction value is greater than a calibrated limit.

Cause:
Faulty Heated Oxygen Sensor
Heated Oxygen Sensor harness is open or shorted
Heated Oxygen Sensor circuit poor electrical connection
Exhaust leaks
Contaminated Heated Oxygen Sensor

Symptoms:
Check engine light