1.9TDI Multitronic won't start after accident


Registered User
Sep 26, 2005
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Suffolk, UK

I have just helped a friend bring home a 2004 A4 1.9TDI multitronic, it was involved in an accident, he bought it bent, had it repaired and have just realised it is refusing to start.

The ignitition switches on fine, DIS says press footbrake to start but no gear position shown in the bottom section (can't remember if it should on not at that point)

Odd thing is that with the key off the gear selector is locked in park, but as soon as the key is turned it is free to move to any position (without the brake pedal pushed) which isn't right.

I have scanned the car for codes, the engine showed

18034 - Powertrain Data Bus: Missing Message from TCU

the ABS showed,

01826 - Sensor for Steering Angle (G85); Supply Voltage Terminal 30
18055 - Check Coding of ECUs on Powertrain Data Bus

18034 again

I could not connect to the transmission.

Apparently the damage to the car was around the base of the A pillar on the drivers side behind which there is various electrical components so speculation is that something has been damaged in there.

Any ideas what to look for?? Help gratefully recieved

I should add that it won't crank, just as if the gearbox inhibitor is working all the time.
Hi there,

Did you solve the problem? I've got exactly same situation but I didnt had an accident. Just was trying to start car but it wont start. Got exactly same codes. Thanks. Lucas
The cause of the problem is almost for sure, a bad connection for the CAN High or CAN Low bus wires, at or near the TCU. Examine the terminals in the harness connector to the TCU, make sure none of the wire terminals are damaged from test probes, etc, and not otherwise bent and unable to maintain contact with the mating pin terminal tightly. The symptom you described, is a classic case of a loose connection, where the symptom alternates with normal operation.

TCU is in with main ECU under wiper panel you have a dodgy connection , could under the TCM where wire feed into car (driver side) or just a bad connection on TCM plug, was the damage on driver side A post if so thats close to where TCM lives.

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