If the sensor output is over 1.08 V under enable conditions, ECM sets DTC P0138.
(This DTC might be caused by the malfunction of Heater circuit, so, check the heater circuit first. )
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Signal check, high | 1. Poor connection 2. Short to power in signal circuit 3. S2 |
Enable Conditions |
•
Dew point end detected
•
Battery voltage > 11V
•
Exhaust Gas temperature = 350℃~800℃
•
No upstream O2 sensor heater error | |
Threshold Value |
•
S2 sensor voltage > 1.08 V | |
Diagnostic Time |
•
5 sec | |
MIL ON Condition |
•
3 driving cycle |
※ S1 : upstream oxygen sensor / S2 : downstream oxygen sensor
