The PCM/ECM monitors rich-lean switching time of rear heated oxygen sensor (HO2S) after fuel cut-off to validate dynamic behavior of rear heated oxygen sensor (HO2S). After detection of fuel cut-off engine operating state, the PCM/ECM measures rich-lean switching time of the rear heated oxygen sensor (HO2S) signal and compares it to the predetermined limit value. DTC P0139 is set when the switching time is bigger than the limit value.
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Slow response(Switching time check at entry in fuel cut off) | 1. Leak in intake or exhaust system 2. Faulty fuel system. 3. Front and rear HO2S connections reversed. 4. Poor connection or damaged harness 5. HO2S contamination |
Enable Conditions |
•
Coolant temperature >73℃(163℉)
•
Downstream O2 sensor readiness detected
•
Downstream O2 sensor pre-heating phase finished
•
400℃(752℉)< Catalyst temperature model
•
0.6V< Downstream O2 sensor signal at entry into fuel cut-off
•
No relevant failure
•
11V < Battery voltage < 16V | |
Threshold Value |
•
Average ratio between measured and maximum allowed rich to lean switching time entering fuel cut-off >1 | |
Diagnostic Time |
•
4 valid fuel cut-off phases | |
Mil On Condition |
•
2 Drive Cycles |
