2020 S4 TDI planetary gearbox failure

[poweller]

Evening all
I own a 2020 S4 tdi which I’ve had since new, and has always been serviced by the main dealer. The warranty expired in March and it recently hit 60k miles. It’s been trouble free until 60k miles but since then it has been plagued with issues and all sorts of warning lights have been popping up, including an Ad blue system failure, gear box malfunction and drive system fault, as well as a squealing noise coming from the engine bay on start up- this is sporadic. The faults generally clear once the vehicle is restarted but I booked it in with Audi for a diagnostic today.. They found issues with the alternator, wiring to the ad blue system and biggest of all, a ‘planetary’ gear box fault which sounds pretty serious- they’ve kept the car for further investigations tomorrow. However, they’ve implied that a new gearbox will be needed so looking at megabucks. £10k was banded about! They did mention they would look at some sort of goodwill as the car is not particularly high mileage and has been maintained by the dealer. Has anyone on here experienced similar issues with their S4 TDI? Do you think I’ve got a reasonable chance of Audi footing the bill? Thanks.

 

[spartacus68]

Sorry to hear your news. I had to re-read the year of manufacture of this car, 2020! Absolutely - I would be looking to Audi to make a substantial contribution towards the gearbox, if not replace it outright. It is worth looking at some sort of extended warranty of these things given the high costs involved. Would be interesting to know how it's failed if they strip it down, but knowing Audi, they will remove and replace and not even dig into the internals. If they play hard-ball take the car to a transmission specialist.

AdBlue faults are well documented. Either injector gets clogged or pump fails. It shouldn't happen, but it does. Unusual for the wiring to be damaged, that said it could be chaffing if it's been routed badly or it's been disturbed in any way. Audi don't use tinned wiring, so could even be oxidisation if it's been exposed somehow. Alternators - not heard anything untoward. Normally they are pretty robust and usually made by Valeo or Bosch.

 

[poweller]

Sorry to hear your news. I had to re-read the year of manufacture of this car, 2020! Absolutely - I would be looking to Audi to make a substantial contribution towards the gearbox, if not replace it outright. It is worth looking at some sort of extended warranty of these things given the high costs involved. Would be interesting to know how it's failed if they strip it down, but knowing Audi, they will remove and replace and not even dig into the internals. If they play hard-ball take the car to a transmission specialist.

AdBlue faults are well documented. Either injector gets clogged or pump fails. It shouldn't happen, but it does. Unusual for the wiring to be damaged, that said it could be chaffing if it's been routed badly or it's been disturbed in any way. Audi don't use tinned wiring, so could even be oxidisation if it's been exposed somehow. Alternators - not heard anything untoward. Normally they are pretty robust and usually made by Valeo or Bosch.

Thanks! Yeah, I’m really shocked, I’ve had a few Audis over the years and they’ve generally been trouble free, perhaps this is a Friday afternoon job.. still waiting for an update off Audi. They did mention chaffing to the wiring so sounds like poor workmanship.

 

[poweller]

Had a slightly confusing update from the dealer today.. the gear box replacement will be covered under goodwill (£11k!) but I’d have to pay the labour costs. However, they then said they could just clear the fault and I could see how it goes- earlier in the week they told me it wasn’t driveable..

Not so good on the other issues, ECU issue with the ad blue system (£2200) and alternator needs replacing (£1900). They won’t cover these issues. Bit of research has discovered they’re both common problems. Think I’ll take it somewhere for a second opinion- has anyone got any recommendations for Audi specialists in midlands or south west? Cheers.

 

[poweller]

I’ve done some more research this evening and am now wondering if the gear box and ad blue warning lights have been caused by the faulty alternator. It was the first issue to manifest and the only issue where there is a clear physical indicator- it sometimes squeals on start up. The other warning lights (ad blue and gearbox malfunction) have only popped up when I’ve forgotten to turn off the start system.

 

[spartacus 68]

Something doesn’t add up here. This is a 2020 car out of warranty back in March but FSH and Audi expect you to pay potentially over £5-6k in labour and parts to have this fixed, even allowing for a free transmission unit worth £11k.

This is my take on it. Get the offer of the goodwill transmission in writing. Clearing the codes and seeing how it goes is poor. The codes registered for a reason, but that said I’ve seen a faulty ABS sensor trigger all manner of warnings.

There is a lack of knowledge at Audi dealerships. Let’s face it, they don’t repair things, they’ll swap it out at the owner’s expense.

If you do opt to get this repaired then you’ve bought a 2 years parts warranty in effect which gives you time to think whether you want to keep the car.

Personally I wouldn’t deal with Audi, if you can find a trusted independent as they will have access to similar diagnostics. You’re in a bit of a catch 22 situation however, as the transmission fault could reoccur down the line, and Audi I suspect will step away from this if you've taken the car elsewhere.

 

[poweller]

Turns out there has been a class action lawsuit against Audi in the US relating to defective alternators on the models with the 48v mild hybrid system. Sounds very similar to the issues I am experiencing.

Audi Electrical System Malfunction Warnings Cause Lawsuit | CarComplaints.com

Audi electrical system malfunction warnings have caused a class action lawsuit that alleges alternator and starter generator problems activate various warning messages to drivers of these Audi vehicles.

m.carcomplaints.com

I think I’ll try and get them to replace the alternator with goodwill and get it in writing that they’ll replace the gearbox if the replacement alternator doesn’t solve it.

 

[The Jargen]

The Gearbox is pretty robust, its the same ZF8HP65A used across various models, it doesn't usually fail. The 48V issue is well documented as you have now found out.