Do-it-yourself repairs

View of the Mono-Motronic fuel mixture preparation unit with air filter removed
1 – pressure regulator;
2 – connector for injector and intake air temperature sensor;
3 – connector for throttle valve potentiometer;
4 – injector;
5 – intake air temperature sensor.

Unfortunately, many injection system checks cannot be performed at home due to the lack of necessary test equipment. However, there is still some scope for work.

The control unit itself cannot be checked using home methods. However, practice shows that faults in it occur very rarely.

Sensors, switches and cable connections are far more often the cause of problems. Therefore, if faults are found, the following procedure is recommended:

PROCEDURE

Make sure the ignition system is in order.

Check the fuel supply.

Carry out a visual inspection of the injection system components.

If the fault is not found in this way, review the fault list at the end of the chapter and check the fault memory in a workshop, and check the suspected component according to the indicated circuit diagram.

Note: if the injection system fails completely, first check fuses No. 13, 21, 25, 27 and 28. All power supply to the Mono-Motronic injection system passes through them.