P1127

P1127

418 Oxygen Sensing Error by means of Short Test, Bank 1 - Below Limit

Diagnosis conditions
- Mixture adaptation performed with the Porsche System Tester 2

Possible fault cause
- Incorrect signal from MAF sensor
- Fuel pressure too high
- Fuel injector leaking
- EVAP canister purge valve open

Diagnosis/troubleshooting

NOTE: If DTC P0445 (fuel tank vent valve - short to ground) is stored, correct this fault first. An open EVAP canister purge valve can lead to the lean threshold being reached.

Part 1:

Part 2:

418 Oxygen Sensing Error by means of Short Test, Bank 1 - Above Limit

Diagnosis conditions
- Mixture adaptation performed with the Porsche System Tester 2

Possible fault cause
- Incorrect signal from MAF sensor
- Intake air system leaking
- Fuel pressure too low
- Volume supply of fuel pump too low
- Fuel injectors fouled

Diagnosis/troubleshooting

NOTE: Air leaks ahead of the oxygen sensors can lead to a fault in adaptation See Check exhaust system for leaks.