Please help before my A6 Quattro bankrupts me...

[skaj19]

I hope someone can help me with this, here goes...

My car is an A6 2.5TDI Quattro Avant 02 plate - a couple of months ago I started getting a couple of intermittent problems; firstly the engine would run fast (1,200 rpm on tickover as opposed to the usual 800 rpm) and at the same time the car would change gear at the wrong time - it would drop down a gear when it shouldn't and/or would not change up when it should until hitting over 4,500 rpm. Secondly - and I don't know if this is related to the first problem - the ESP light would come on and stay on until I restarted the car. Again, I stress that both problems were intermittent.

Anyway, two weeks ago I lost all transmission and the gearbox went into "PRNDS" failsafe mode. I had the car taken to a transmission specialist and I had to have the whole gearbox rebuilt for two grand. The guy showed me all the damaged cogs, clutch and hydraulic parts that had come out, it was buggered. He had also checked the ECU which was clear and all was now good, or so I thought.

I picked the car up Friday; on Saturday - I think you can guess where this is going - the same problem came straight back; the car started running too fast during a drive and was changing gear when it shouldn't. Sunday and today, the car runs fine.

Given that the gearbox is now (internally) all new, and the ECU is producing no faults, I can only surmize that the EMS is in error in both causing the engine to run too fast which is having the knock-on effect of incorrect signals being sent to the gearbox. The problem is that I'm not getting any EMS fault registering on the dashboard and nor is there any showing when the RAC guy (who I called out Saturday) ran his diags.

Can anyone help? I've spent a ton of cash on this already and it seems that I've had the effect of the problem fixed, but not the cause... Help!

(PS: I've been reading all about various problems people have had with the Multitronic gearbox, but this being the Quattro I'm right in saying this has the Tiptronic box, right?)

[kite]

That's right, you don't have multitronic. A vagcom scan would be the first thing to try, see if any faults are logged.
Look in the vagcom section for a member in your area goal a scan.

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[skaj19]

Thanks Kite,

Please excuse my complete ignorance, what exactly is a Vagcom scan?

[kite]

Vagcom= diagnostic software.
Where in the UK are you?

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[kite]

I see your in London.
Chris( adamss24) is in north London and is good around a V6. Try sending him a private message

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[skaj19]

Thank you very much for your help mate but I'm actually about 30 miles west of London in south Bucks, I'll take a look in the section you mentioned, hopefully there's someone not too far away, thanks again mate.

[kite]

I'm in Bracknell and have VCDS if that's any nearer for you.

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[NickPicks]

And I'm in High Wycombe if it's any closer. I can do you a vagcom scan tomorrow (laptop's at home today).

[skaj19]

Nick, thank you so much - that would be great. I've just tried sending you a PM but my post count is not high enough to do so, any chance you could send me one with your number on? Thanks again mate.

And thank you Kite for your equally kind offer, what a pleasant bunch on here.

[JamesSvr6]

The coolant temp sensor makes the car idle at 1200rpm+ if it's faulty. Could be worth replacing this as it's cheap (under £10) and 5mins to DIY.