Audi A4 B6 cab electrical issue - diagnosis?

[The Stiglet]

My mother in law has a very low mileage, garaged, A4 cab, 1.8T, auto (B6). She continues to have the car regularly serviced and maintained by Audi but yesterday the transmission started to slip and then eventually completely disengaged with me in the car. I told her to pull over and see if restarting the car would clear the problem. All the warning lights came on the dashboard and the vehicle wouldn't start. We went for lunch and came back a couple of hours later and I asked her to try again - the car started and moved with no problems. We then completed a 5 mile urban journey.

She said she smelt some 'burning' on the motorway the day before and later that day the car refused to find a gear at a junction. She managed to get it into reverse where it crept back slowly but had experienced no other issues. Audi had recently changed the pads but that's all.

There was no shuddering, juddering or anything that felt mechanical disintegrating so I've concluded that it's got to be electrical.

Any ideas guys?

[SteBrown91]

Unless it's Quattro then the gearbox is a multitronic cvt box isn't it? So the slipping and the burning could indicate the box has let go, and the earlier multitronics are pretty unreliable

[The Stiglet]

SteBrown91 said:

Unless it's Quattro then the gearbox is a multitronic cvt box isn't it? So the slipping and the burning could indicate the box has let go, and the earlier multitronics are pretty unreliable

It's not a quattro but I don't know about the gearbox type. Why would the car not start though and then after a couple of hours all is okay? I thought it was the torque converter having a fit, unlocking and then locking again but I had issues like this on an E39 and it turned out to be electrical requiring some new fuses and wiring.

[Dr G]

Yup, that's a multitronic/CVT and sadly from an era where they're not famed for their durability.

The clutch-pack, gearbox ECU and box internals can all give grief. It wants to go to an Audi specialist or really good gearbox man for diagnosis.

[The Stiglet]

New 'gear control box' required. Audi quote £1,919 inclusive of labour and VAT.

What is a gear control box? Gearbox ECU? Or mechanical?