P2187

P2187

Lambda Control Adaptation In Idling Range, Bank 1 (RKAT1) - 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)
- Mass air flow less than 35 Kg/h
- Engine speed less than 1,160 rpm

Diagnostic conditions - V6
- Battery voltage between 10 V and 16 V
- Lambda control active
- Engine temperature greater than 60 °C
- Engine speed less than 960 rpm
- Mass air flow less than 30 Kg/h

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
- Fuel pressure too low
- Fuel pump delivery too low
- Mechanical fault in fuel injectors
- Positive crankcase ventilation leak
- Oil filler cover leak
- Leak in exhaust system
- Mechanical fault in tank vent valve (stuck open)
- Tank vent valve driver fault

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
- The diagnosis is intended to indicate a positive deviation of more than 6% (enrichment) of the lambda control adaptation in the range near idle speed (RKAT = 6%). The most frequent cause of faults is leaks (secondary air) between the throttle valve and intake valves or at the engine ventilation.
- Opposed adaptation values in connection with misfires indicate that the timing is out of adjustment.
- 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.