Audi A5 electrics mayhem

[CJUsher]

Hi all

I've been having some interesting issues with my 2008 Audi A5 3.0L

Initially the power steering would suddenly stop working (heavy when driving slow and super light like ICE when driving quickly). If the car was shut down and restarted the problem stopped for a while then reoccurred (no dash fault lights). However, this problem has grown.

Now the car drops the power steering, all of the lights on the dash come on (ESP, EM, parking brake fault) followed by the rev counter dropping to 0 then the spedometer dropped to 0. Usually I lose the rest of the dash shortly after this.

I've had it diagnosed by Audi and a third party Audi specialist. Audi recommended a new battery, which hasn't fixed anything. Audi third party specialist have seen the problem first hand as I dropped it off to them with no dash and no power steering. When the car is turned off from this point it won't turn back on again until the battery has been disconnected and reconnected after 60 seconds.

They couldn't find a thing wrong with it for the 2 days they had the car. Checked fuses etc and battery is fine.

Anyone had similar issues? Car used to run beautifully until this started happening. 114,000 miles.

Thanks for any help you can suggest.

[aliperry]

Morning Usher,

I've got a 2009 A4 3.0 TDI which has similar symptoms. The electric parking brake had a mind of it's own and then the car would start and then just cut out. Key wouldn't release and the door locks would go mad.

I thought it was a duff battery at first but turned out to be some corroded wires at the rear by the lights (drivers side). These wires go the Central Control Module which was causing all the issues.
There are vents which are supposed to release the pressure but can go bad and let water in the other way.

Have a read here:
http://www.a5oc.com/forums/a5-general-q/20391-wet-...

Hope that what it is but it sounds very similar!

[va1o]

I had issues with water ingres on my 2008 S5 so I think it's probably quite common. Symptoms weren't as bad though, just random bulb warning errors and KESSY disabled itself.

[Rich_W]

You've got 2 problems.

First one is most likely a PAS pump or potentially a rack. Try pump first unless the rack is leaking. Get whoever to take the gaitors off the rack as they leak into the gaitors.


Second one sounds like a power supply fault. Or potentially a gateway control unit issue. Or perhaps just a dash insert faulty. We know the battery is ok as it's new. Need a fault code to narrow it down. Gut would be gateway unit. Which I can't honestly remember if it's a separate unit or in the dash insert anyway..

[Dr G]

Your Christmas tree of warning lights does point towards a wiring issue rather than specific component failures although faults like this can be a pig to find and need a really skilled diagnostic technician. Even then there's an element of luck involved.

A good place to start from could be looking for signs of water ingress by pulling trims, squishing sound deadening etc.

The most common wet spot in an A5 is the inside of the NSR quarter (where the MMI electronics live) but the faults this causes don't sound like yours.

[CJUsher]

Update:

Had a look around the rear light clusters as suggested from you all - some slight corrosion was found on the bulb terminal prong (one of the bulbs pulled half the prong off as it was fused to it!).

All affected lights have now been replaced and so far (touch wood) there hasn't been an issue.

Thanks to everyone who has responded. I'll give the car a couple of days and see if the fault reappears.