12A701 - P0138 (DME)

12A701 - P0138

Information saved in
DME

Fault code
12A701 - P0138

Fault text
Oxygen sensor after catalytic converter, electrical: Short
circuit to B+

Fault description
The diagnostic function monitors electrical status of the
oxygen sensor behind catalytic converter.

Condition for fault identification
Test condition:
The fault is recognized when an electrical malfunction is
present in the oxygen sensor behind the catalytic converter.
Potential problem source(s):
- Defective wiring harness
- Oxygen sensor behind catalytic converter defective
- Defective DME
Terminal condition: none
Voltage condition:
- Onboard electrical system voltage between 9 V and 16 V
Temperature condition:
- Engine warmed to normal temperature, more than 80 °C
- Exhaust-gas temperature at post-catalyst oxygen sensor not
higher than 800 °C
Time condition:
- Active heating activation more than 1 min.
Other conditions:
- Engine ON

Condition for fault memory entry
This fault is logged in the control module's fault memory
immediately.

Action in service
- Check the connection between the DME and the oxygen
sensor behind catalytic converter
- Replace oxygen sensor behind catalytic converter
- Replace DME

Fault effect and breakdown warning
Breakdown notice:
Continued driving is possible, but because the oxygen
sensor is not ready for closed-loop control, conversion of
exhaust gases in the catalytic converter will be seriously
impaired.
Possible apparent symptoms:
MIL lamp on after second driving cycle

Driver information
Warning light:
- ECE emissions warning lamp: on
- ECE electronic engine power reduction: on
- CC message: on
- US emissions warning lamp: off
- US electronic engine power reduction: off
- CC message: none

Service instruction
None