12BD90 - P2097 (DME)

12BD90 - P2097

Information saved in
DME

Fault code
12BD90 - P2097

Fault text
Oxygen sensor before catalytic converter, plausibility:
mixture after catalytic converter too rich

Fault description
The diagnostic function monitors the voltage of the pre-
catalyst oxygen sensor and compares it with the voltage of
the oxygen sensor behind the catalytic converter (at lambda
= 1).

Condition for fault identification
Test condition:
The fault is recognized when the lambda signal from the
pre-catalyst oxygen sensor deviates too much from the
lambda signal from the oxygen sensor behind the catalytic
converter.
Potential problem source(s):
- Defective wiring harness
- Defective oxygen sensors
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
- No diagnostic fault codes logged indicating a mixture fault

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

Action in service
- Inspect wiring harness between oxygen sensors
before/behind catalytic converter and DME
- Replace oxygen sensors before and behind catalytic
converter

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