ECM checks output signals from HO2S under detecting condition. ECM judges it's signals too slow and sets P0139, if output signal from rear HO2S isn't increased up to specification level within a short time after fuel cut.
(This DTC might be caused by the malfunction of Heater circuit, so, check the heater circuit first.)
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Slow response | 1. Poor connection 2. leak or clog in intake air system 3. Injector 4. Fuel pressure 5. S2 |
General Enable Conditions |
•
Dew point end detected
•
Fuel feed back control active
•
Exhaust Gas temperature is between 350℃ and 800℃.
•
No upstream O2 sensor heater error
•
Fuel Cut-off condition
•
Rear O2 sensor heater monitoring - completed | |
Threshold Value |
•
S2 signal is higher than 0.15V | |
Diagnostic Time |
•
2 sec. | |
MIL ON Condition |
•
2 driving cycle |
