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 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.