S-Line A4 TFSI 2.0 - It's all gone horribly wrong...

[ChrisBr]

Googling is giving me different responses but nothing that identifies my exact problems, walkthroughs that must be for different models etc.

Car is a late 2008 Audi S Line Avant, 2.0 TFSI



Thursday - Brake Malfunction warning comes up on the dash, handbrake button is flashing. Switch the car on/off and it's fine, no problem whatsoever.

Friday - Cruise control has stopped working, the handbrake wasn't auto-releasing when trying to drive off. EPC light comes on and stays on.

Saturday - Car won't start - revs flick up to about 200rpm but it doesn't ever fire properly, and the handbrake is stuck on again. Keep trying and eventually it fires up.



RAC plugged the diagnostics in and I got the following error codes:

P172400 - Immobiliser signal incorrect
P308200 - Clutch position sensor impausable
O0473 - Parking Brake Control Unit Fail


So, the first thought would be to change the clutch switch as per advice found from googling, but what part do I need and where on earth in the car is it? RAC couldn't find it under the steering column, and I don't know what it looks like.

Brake Control Unit - is this the actual switch on the centre console, or is this a problem somewhere else on the car?


I find it quite bizarre that all of these electronic things would fail at the same time, so is it possible that one part has messed up the rest, or maybe one error is giving erroneous signals to other sensors?

I'm totally at a loss with this, and really can't afford dealer labour fees unless absolutely necessary - hoping that this is a fix I can do in the garage at home...

[kite]

I would get the battery checked first.
Audi cars are quite sensitive to low voltage.

[Crasher]

Yes it could be low battery voltage, enough to make the stater turn but not enough left to make it run.

[ChrisBr]

Sunday - Ignition lock or something now, the startup procedure won't even try - clutch down, put the key in, it won't start but goes into Ignition. You can't remove the key until it says 'Ignition On' after 10-15 seconds and then you can remove it as per normal procedure.

I will try another battery, but I would be amazed if a battery stopped the cruise control, startup, sent a wrong transponder signal from the key and broke the parking brake all at the same time..

Damn thing is now left at my girlfriends - back to driving 1960's technology this week!

[Crasher]

I will be surprised if a new battery DOESN'T sort everything, it is all indicative of a dead cell.

[sportq]

I will try another battery, but I would be amazed if a battery stopped the cruise control, startup, sent a wrong transponder signal from the key and broke the parking brake all at the same time..


Do your coming home lights still work? My battery gave up last year the first sign was that these lights wouldn't come on when I used the remote to lock and unlock that car. There were other weird unconnected things happening too. It's pretty smart a managing limited battery capacity by disabling system, maybe too smart in your case :)

For anyone with the original battery on a +5 year car it's worth getting someone with VCDS to enable the battery level monitor (this is possible with MMI high and low packages) just to keep an eye on it. When I got the car I thought it was normal for the battery to vary between 100% and 80% capacity. Once I got the new battery installed it never dropped below 100% ever.

Pete

[ChrisBr]

The lights were coming on, just wasn't starting. I miss the simple technology and cheap, quick fixes!

[Crasher]

If it is a flat battery, what could be simpler or more traditional? On the subject of simple tech, would you trade in your ABS, air bags, air con, power steering etc etc?

[s7gpt]

any update on this - did battery sort it then ?