P0138

Condition







The control module takes as its starting point an initialization value for the probe voltage which is at least 0 V and a maximum of 5 V. If probe heating is active and at least 1 fuel shut-off has been made, the heated oxygen sensor (HO2S) maximum value must exceed 0.6 V and the minimum value must be below 0.1 V. Diagnostic trouble code (DTC) ECM-2200 is stored if these limit values are not achieved after approximately 5 minutes and both accumulated and actual heated oxygen sensor heating has reached certain limit values.

Substitute value
Rear heated oxygen sensor (HO2S) control is disabled.

Possible source

Signal too high
- signal cable short-circuited to supply.

Signal too low
- short-circuit to ground in signal cable
- open-circuit in signal cable
- defective rear heated oxygen sensor (HO2S).

Fault symptom[s]
None.