Trouble Shooting The Adjusting Unit (VANOS)

Interrogate fault memory of engine control unit.
If no faults are stored in memory, refer to Checking operation of VANOS.

M50 B20:
M50 B20 engines are fitted with an engine control unit from "Siemens".
Designation: MS 40.1
Faults which could be stored in control unit fault memory:
1 Feedback of intake camshaft position. If camshaft is not adjusted or only adjusted inadequately after activation and triggered operation, this is stored in fault memory.
2 Testing of final stages
3 Short circuit to positive
4 Short circuit to earth
5 Breaks in wiring

M50 B25:
M50 B25 engines are fitted with an engine control unit from "Bosch".
Designation: DME M 3.3.1
Faults which could be stored in control unit fault memory:
1 Testing of final stages
2 Short circuit to positive
3 Short circuit to earth
4 Breaks in wiring