HELP! - Warning lights for ABS, Oil and Brakes and Limp Mode

[nettie]

Have had ongoing problems with 1999 Audi A6 (LOVELY car apart from this...)

For some time car has had a judder if it is idling. I have been told this is a leaking rocker cover gasket. I thought I had this and the brake pads done at a local garage, but problem wasn't fixed. Then started to get brake light warning. Went back to garage, he did something with a sensor. Also turned out he had only replaced one rocker cover gasket not both of them ( he doesn't believe this is causing the judder though).

Could live with the judder, mostly rural driving so no idling. However, the other day car was driving beautifully when suddenly there are lots of warning lights. Brakes, ABS and Oil and seemed to not want to go past 2nd gear (it's automatic). I assume this is 'limp mode'.

This is now happening a lot will drive for miles with no problems and then goes crazy. First time I didn't think I should drive it home so went to nearby local specialist and they replaced the oil pump to no effect. They said could be a number of things like needs new gearbox, all of them were very expensive.

Drove home to my local mechanic in 'limp mode'. He has been tinkering, checking electrics etc.

Doesn't seem to actually be anything mechanically wrong with the car just the onboard computer is CRAZY! How can it drive beautifully for miles and miles if it has a mechanical fault. Seems like such a waste of a good car!

I am at a loss as to what I should do next. I love the car and when it works it is great. Trying to weigh up whether to get a new car for £2000, but nothing is as good as my current car and would rather spend the money fixing it but everything I have done so far seems like a dead loss.

Can anyone offer any suggestions / new perspectives?

[Yoyo42]

I had something similar and it was a problem with the ABS controller when it got hot. You can test it by pulling the plug on the hydraulic block by the screenwash bottle. This doesn't interrupt the hydraulic circuit, it just disables the ABS but leaves the brakes intact, so it's safe to test drive. I can't remember if I had to reset the error codes or not, but I know it instantly fixed all the issues.

If it *is* that you can take the ABS controller off the hydraulic block and send it to get it fixed (with the car still drivable) - I sent mine to BBA Remanufacturing and it came back a few days later working perfectly. Cost about £150 IIRC.

The actual issue is that the main power connection inside the hybrid ABS controller uses an aluminium connection instead of the gold wires used for all the other connections and it gets fatigued. When it goes the controller sucks power from the data bus instead which causes false alarms in almost all of the other circuits, causing the gearbox fault codes, limp mode, no rev counter etc.

Takes a few minutes to try it, so why not.