P0161

12B801 - P0161

Information saved in
DME

Fault code
12B801 - P0161

Fault text
Oxygen-sensor heater after catalytic converter 2, function:
internal resistance too high

Fault description
The diagnostic function monitors the internal resistance of
oxygen sensor 2 behind the catalytic converter.

Condition for fault identification
Test condition:
The fault is recognized when the internal resistance of the
post-catalyst oxygen sensor 2 is greater than 5000 ohms.
Potential problem source(s):
- Oxygen sensor 2 behind catalytic converter too strongly
cooled by external factors (such as ice formation)
- Defect in wiring harness to oxygen sensor 2 behind
catalytic converter
- Oxygen sensor 2 behind catalytic converter defective
Terminal condition: none
Voltage condition:
- None
Temperature condition:
- Exhaust-gas temperature less than 700 °C
Time condition:
- None
Other conditions:
- Engine on
- No additional diagnostic fault codes logged

Condition for fault memory entry
This fault is logged in the control module's fault memory if
it remains present for longer than 400 sec.

Action in service
- If possible determine whether fault has been caused by ice
formation
- Check wiring harness to oxygen sensor 2 behind catalytic
converter
- Replace post-catalyst oxygen sensor 2

Fault effect and breakdown warning
Breakdown notice:
- none
Possible apparent symptoms:
- none

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

Service instruction
- none