12A102

12A102 - P2270

Information saved in
DME

Fault code
12A102 - P2270

Fault text
Oxygen sensor after catalytic converter, system check:
signal fixed at lean

Fault description
The diagnostic function monitors whether the voltage of the
oxygen sensor behind catalytic converter remains stuck at a
low value.

Condition for fault identification
Test condition:
The fault is recognized when the voltage of the oxygen
sensor behind the catalytic converter remains consistently
too low.
Potential problem source(s):
- Mixture too lean
- Leak in exhaust system on engine-side of catalytic
converter
- 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 temp, above 80 °C
Time condition:
- None
Other conditions:
- Engine on
- Steady-state at low to medium partial load

Condition for fault memory entry
The diagnostic fault code is logged when the fault remains
present for longer than 10 min.

Action in service
- Check the connection between the DME and the oxygen
sensor behind catalytic converter
- Determine whether the oxygen sensors are in the wrong
mutual locations
- Check the exhaust system upstream from the oxygen
sensor for leaks
- 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 lights up when fault is detected in two consecutive
driving cycles

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