Manufacturer Code Charts: 129002

129002 - P0131

Information saved in
DME

Fault code
129002 - P0131

Fault text
Oxygen sensor before catalytic converter, signal lines: Short
circuit to earth

Fault description
The diagnostic function monitors the controller in the DME.

Condition for fault identification
Test condition:
The fault is recognized when an electrical malfunction is
present in the oxygen sensor before the catalytic converter.
Potential problem source(s):
- Defective wiring harness
- Oxygen sensor before 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 temp, above 80 °C
Time condition:
- None
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 wiring harness between pre-catalyst oxygen sensor
and DME
- Replace pre-catalyst oxygen sensor
- 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 lights up after 2nd driving cycle
- Higher exhaust emissions
- Higher fuel consumption
- Surge

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