Engine won't start, cranks after start attempt (Solution)

1.9L direct injection engine.
AHU, AFN, AEY
Engine won't start.
The error sometimes occurs sporadically.

Cause:
Power supply relay for the motor control unit is defective.

Solution.
Testing the voltage supply of the engine control unit.
In case of a defect, replace the relay.



1.9 l SDI/TDI
AFN, AHU, AEY, AGD, ALE
Engine revs up to approximately 2,000 RPM after starting, experiencing a lack of power.
Approximately 120 km/h with error code 1237, fuel valve N109.
Warning light flashing.

Cause:
The electromechanical shut-off valve is used in the safety self-diagnosis system.
identified as defective.

Solution:
Repair of the electromechanical shut-off valve using the...
Part number 028 198 135.

Hi Michael,

Quote:

1.9 l SDI/TDI AFN, AHU, AEY, AGD, ALE Engine revs up to approximately 2,000 RPM after starting, experiencing a lack of power. Approximately 120 km/h with error code 1237, fuel valve N109. Warning light flashing. Please provide the German text you would like me to translate into English. Cause: The electromechanical shut-off valve is triggered during the safety self-diagnosis. identified as defective. Series: Modified shut-off valves. From 04.98. Repair of the electromechanical shut-off valve using the... Part set 028 198 135.

Do you also know the cause of the "defect detection"? For example, I could imagine a coil resistance falling outside the tolerance range stored in the motor control unit.
But if the engine still starts, then it can't be a "real" defect. Does the EDC also detect if the device doesn't close properly?

Otherwise: great idea with the "insider documentaries"!

I fully agree with Ulf's statement - a great idea!

@Rainer: Perhaps we should try to compile this information in a concise manner, provided there are no legal objections, because for many common questions (e.g., the shaking when idling), a brief reference would suffice.

Best regards,

Jan.

Hello Ulf,

Unfortunately, I am not aware of the exact causes either. Mine.
It is believed that the system checks the current flow when the valve is activated.
Therefore, it is quite possible that the winding values are outside the...
Tolerance or very close to it.

Michael.