P0131

P0131

Oxygen Sensor Ahead Of Catalytic Converter, Bank 1 - Nernst Voltage Line - Below Limit

Diagnostic conditions
- Battery positive voltage between 10 V and 16 V
- Time after the engine is started longer than 10 seconds

Possible cause of fault
- Check Nernst voltage line for short circuit to ground
- Oxygen sensor faulty (internal short circuit or intercore short circuit)
- DME control module faulty

Affected terminals
DME control module connector A, pin 70, oxygen sensor connector in front of catalytic converter, bank 1, pin 1

Diagnosis/troubleshooting

NOTE:
- Do not use contact spray on the oxygen sensor plug connections as this may cause irreparable damage to the wiring (contamination of the oxygen sensor via the reference air channel).
- Do not confuse oxygen sensor ahead of catalytic converter and oxygen sensor behind catalytic converter as this will cause implausible fault entries.

Distinguishing feature of both sensors:







Oxygen sensor in front of catalytic converter (LSU) has a six-pin connector







Oxygen sensor behind catalytic converter (LSF) has a four-pin connector