Audi B8 RS4 gearbox issues

[Sport_Turismo_GTS]

Car was serviced last week, all running fine beforehand and immediately afterwards, including a 400mile trip at the weekend.

Travelling to a physio appointment, I remember thinking that the back end of the car seemed a bit noisy and then noticed some very abrupt gear changes - I think from 1st to 2nd and 2nd to 3rd. Driving home it seemed to be quieter and the gear changes back to normal, but then I got an error message “gearbox error, reverse gear unavailable, ok to continue driving”. Shortly after I had a TPMS error message.

I got home, turned the car off and then restarted, and the gearbox error had disappeared (but not the TPMS error), and I was able to manoeuvre the car (including reverse) onto the drive.

This morning, I had no errors and the car was driving normally until suddenly I had a different error message “gearbox overheating, modify your driving style” - this was after 5mins of sedate (30mph) driving.

I drove straight to the local Audi garage (who had done the service last week, including the relevant gearbox oil) and is now with them for diagnostics.

A quick search online suggests mechatronic gearbox might need to be repaired / replaced?

Anyone with experience of this issue?

[Dr G]

Box issues on those are fairly rare if correctly maintained; I've bought and sold dozens of them, and I think only seen one proper failure (cracked casing) among a few more minor problems.

There have been incidences of the gearbox oil cooler leaking and allowing coolant to mix with the gear oil.

The mechatronic module itself can simply fail, and would give symptoms like those you're experiencing. I've once had a temperature sensor cause gearbox weirdness too.

How many miles has the car done, and have oil changes (box and front final drive) been observed?

[Sport_Turismo_GTS]

Dr G said:

Box issues on those are fairly rare if correctly maintained; I've bought and sold dozens of them, and I think only seen one proper failure (cracked casing) among a few more minor problems.

There have been incidences of the gearbox oil cooler leaking and allowing coolant to mix with the gear oil.

The mechatronic module itself can simply fail, and would give symptoms like those you're experiencing. I've once had a temperature sensor cause gearbox weirdness too.

How many miles has the car done, and have oil changes (box and front final drive) been observed?

Thanks. The car has done 72,000 miles and has been maintained by Audi exactly in accordance with the requirements.

[Dr G]

So was that the 80k fluids being done ahead of schedule then?

Exactly what fluids did they change? S Tronic and front final drive? Did the actually put oils in? Did they put new sump plugs in? Did they overtighten them? Did they get the oils the wrong way round?

Whilst it's possible the failure is a complete coincidence if it had left there with an oil leak (or oiling mistake) a few hundred miles feels right for that to manifest.

[Sport_Turismo_GTS]

Dr G said:

So was that the 80k fluids being done ahead of schedule then?

Exactly what fluids did they change? S Tronic and front final drive? Did the actually put oils in? Did they put new sump plugs in? Did they overtighten them? Did they get the oils the wrong way round?

Whilst it's possible the failure is a complete coincidence if it had left there with an oil leak (or oiling mistake) a few hundred miles feels right for that to manifest.

Yes, standard service plus these additional items which were due fairly soon, an which I wanted to get done ahead of selling the car.

The car is under Audi extended warranty, so I don't expect to have to pay for this!

[ninjag]

My money will be on the main dealer making a colossal mistake of some sort. But then I have a huge distrust of main dealers.

Maybe they only did the first fill and didn't do the transmission warm up procedure and subsequent second fill leaving the dual clutch side short on fluid?

[Madelvic]

Chris Harris wrote about this in detail with his B8 S4. I had exactly the same issue. £3k part on a long wait-list but Audi paid 60% goodwill on a 6 year old car

[Dr G]

This doesn't sound much like the issue with early B8 S4 boxes.

[Sport_Turismo_GTS]

ninjag said:

My money will be on the main dealer making a colossal mistake of some sort. But then I have a huge distrust of main dealers.

Maybe they only did the first fill and didn't do the transmission warm up procedure and subsequent second fill leaving the dual clutch side short on fluid?

Well, they took the car back, investigated the issue 'topped the fluids' up and the car is driving beautifully again. I have requested paperwork to summarise the issue they found and their resolution process.

In the meantime, I have a goodwill bottle of whisky.

[ninjag]

Sport_Turismo_GTS said:

ninjag said:

My money will be on the main dealer making a colossal mistake of some sort. But then I have a huge distrust of main dealers.

Maybe they only did the first fill and didn't do the transmission warm up procedure and subsequent second fill leaving the dual clutch side short on fluid?

Well, they took the car back, investigated the issue 'topped the fluids' up and the car is driving beautifully again. I have requested paperwork to summarise the issue they found and their resolution process.

In the meantime, I have a goodwill bottle of whisky.

Hmm, it does sound like the second fill wasn't done. Hopefully they didn't forget to get it to the right temp before doing it as well.

[Dr G]

It does "feel" like an oil fill issue, could have been not enough, or they've mixed the two up, or reused the old sump plug...