P0491

P0491

Diagnosis information - Control unit DME (DFI)

Secondary air system Bank 1

Diagnostic conditions
- Short test perform
or:
- Diagnosis starts under the following conditions::
- Engine running , at:
- Ambient temperature > 5 °C (°F)
- Engine start temperature 5 ... 32 °C (°F)
- Secondary air injection Active

- none of the following faults stored : Oxygen sensor in front of catalytic converter, Coolant temperature sensor Engine, Camshaft adjustment, Ambient pressure, Ambient temperature

- Diagnosis ends under the following conditions :
- Oxygen sensor in front of catalytic converter not ready for operation
- Period of time total (Diagnosis) exceeded (depending on: Engine start temperature)

- Diagnosis will be interrupted for as long as the following conditions exist :
- Engine speed > 3,500 1/min
- Mass air flow > 750 mg/stroke
- Overrun phase(s)

Possible fault causes
- Catalytic converter Faulty (broken)
- Lead Secondary air injection leaks
- Secondary air valve Bank 1 stuck / frozen
- Air-inlet duct (Engine) Narrowed /fouled
- Fuel/air mixture preparation not adapted

Fault setting condition(s)
- Deviation Lambda control Actual value [] Nominal value
- The diagnosis checks whether deviation of the oxygen sensors is as expected upon activation.