DTC Description

Due to possible oxygen sensor defects (e.g. reference air poisoning) or faults in the injection system (e.g. leaking fuel injector), the rear oxygen sensor may not provide the expected lean or rich signal level during fuel cut-off condition or full load condition. Hence, the oxygen sensor signal is checked for plausibility during these engine operating states. There are 2 cases in which DTC P0140 sets:

1. Signal monitoring during fuel cut-off: The PCM monitors rear O2 sensor signal level during fuel cut-off, which normally shows near 0V and sets DTC P0140 when signal level is too high.
2. Signal monitoring after fuel cut-off: The PCM monitors rear O2 sensor signal level after leaving fuel cut-off, and sets DTC P0140 when signal remains at or below 0.6V.