P2177

P2177

Lambda Control Adaptation In Lower Load Range, Bank 1 (FRAU1) - Above Limit Value

Diagnostic conditions - V8
- Battery voltage between 10 V and 16 V
- Lambda control active
- Engine temperature greater than 60 °C
- Time after engine starts between 250 and 350 seconds (USA)
- Time after engine starts between 302 and 402 seconds (RoW)
- Engine load between 18% and 70%
- Mass air flow between 50 Kg/h and 320 Kg/h
- Engine speed - for naturally aspirated engines between 800 rpm and 3,520 rpm
- Engine speed - for turbo engines between 920 rpm and 3,520 rpm

Diagnostic conditions - V6
- Battery voltage between 10 V and 16 V
- Lambda control active
- Engine temperature greater than 60 °C
- Engine load between 16% and 50%
- Mass air flow between 40 Kg/h and 240 Kg/h
- Engine speed between 1,200 rpm and 4,200 rpm

Possible fault cause
- Hot-film mass air flow sensor 1 and / or 2 faulty (setpoint voltage with stopped engine and ignition on = 0.9 to 1.1 V)=> see Actual values, Filter [ DME mass air flow ], [ Mass air flow 1 (sensor) ] + [ Mass air flow 2 (sensor) ]
- Intake system leak
- Leak in exhaust system (drawing in fresh air)
- Fuel pressure too low
- Mechanical fault in fuel injector(s) (stuck)
- Fuel pump delivery too low

Affected pins
DME control unit plug A, pin 29, and pin 5 of hot-film mass air flow sensor 1
Not V6 - DME control unit plug B, pin 109, and pin 5 of hot-film mass air flow sensor 2

Diagnosis/fault finding
- Diagnosis should indicate a positive deviation (enrichment) of more than 30% of the lambda control adaptation in the lower load range (FRAU greater than 1.3).
- V8 only - If this fault is set, both hot-film mass air flow sensors must always be tested because the main filling signal is calculated from both signals.