P1073

P1073

Diagnosis information - Control unit DME (DFI)

Mass air flow range near idle speed, implausible too low

Diagnostic conditions
- Idle speed more than 2 Minute(s)
- Trip with different operating conditions
- none of the following faults stored: Intake manifold pressure sensor, Throttle adjusting unit, Ambient pressure sensor, Intake air temperature sensor, Speed sensor, Valve lift control, Camshaft adjustment, Intake pipe switchover

Possible fault causes
- Oil filler cap was opened while engine was running (e.g. to top up oil)
(See Environmental condition 6 for first fault occurrence [SE10 Engine compartment lid open])
- Throttle valve adaptation performed while boundary conditions are violated. (See [Information] 2)
- Throttle adjusting unit soiled
- Exhaust system Blocked / Cross section Narrowed
- Intake manifold pressure sensor - Electrical plug connection loose, oxidized, corroded, interrupted
- Tank vent Faulty - Closed (mechanical / electric)
- Fault in area Intake manifold pressure sensor, Throttle adjusting unit, Ambient pressure sensor, Intake air temperature sensor, Speed sensor, Valve lift control, Camshaft adjustment, Intake pipe switchover

Fault setting condition(s)
- Impermissibly large deviation of the measured air mass from the calculated air mass. (See [Information] 1)

INFORMATION:
1. In this diagnosis, the intake system between the throttle valve and the engine (intake valves) is monitored.
- A mass air flow is calculated from the signals from the throttle potentiometer, engine speed sensor, intake air temperature sensor and ambient pressure sensor as well as other engine operating values.
- The calculated mass air flow is compared with that measured by the pressure sensor.
- A deviation may be due to both the calculated mass air flow and the measured mass air flow.

2. A note to this effect is stored in the environmental data for the fault entry value [XX-Status of throttle valve adaptation conditions].
- The value indicates whether the throttle valve was taught under violated boundary conditions.
- 0 ... 127 = Throttle valve was taught under the correct boundary conditions.
- 128 ... 255 = Throttle valve was taught under violated boundary conditions.