48v system failure

[ducnick]

I couldn’t find much in the forum so I thought I would mention it here as a warning.

All Audis that use the 48v battery and starter generator since approx 2016 are potentially prone to a very expensive failure. This included my 60k mile, 2019 q7 50tdi, but it runs right up to q7/8’s being built today.
The generator circuit of the starter generator fails and you get an Amber warning light telling you about an electrical system failure and stop start is unavailable. The car starts and drives normally. If you drive it (which the dealer will tell you is fine to do) the 48v battery will be flattened and the power steering will shut down.
The generator will cost you approx £2000 to replace at a dealer. If the battery is killed, that costs approx £1500 to replace. Obviously the parts are all out of stock and your dealer will take at least 2 weeks to get the parts and find an engineer qualified on the hybrid system to fix it.
These failures are big news in the USA where most Audis seem to use the same components and there is the normal class action lawsuit going on. For reference it doesn’t appear to be age or mileage related in the USA with reports of it occurring at all sorts on mileages and even on very new cars.

Anything with the 50 TDI, 45tdi, 55tfsi engines are affected.
Strangely the Porsche cayenne isn’t affected as they use a different system. The v8’s don’t appear to be affected either. Presumably the vw toureg is also subject to this failure.

If it happens to you, my advice is to not drive it more than 5 miles then get it on a 12v battery charger and leave it on there until Audi can trailer it away. If you put it on a 12v maintenance charge it will automatically keep the 48v battery charged and healthy.

The good news is that this is covered by your Audi warranty if you have one. Aftermarket warranties may not be so accommodating.

Edited by ducnick on Wednesday 10th April 07:58

[FMOB]

Owning a 2021 S6 Avant, why am I not surprised.

I got the car pegged as a pile of crap that I regret buying.

[Aluminati]

Just to add, make sure it’s a Lithium battery charger…

[Ollie04TT]

About to put a deposit down on a 21' Q7 55tfsi today. Been told it has a fault with start/stop and engine light on but they're getting it fixed for me. I assumed it was probably just an MMI fault or something. The car has only done 50k miles. Thank you greatly for bringing this to my attention.

Other than that, has the car been reliable?

[FMOB]

Ollie04TT said:

About to put a deposit down on a 21' Q7 55tfsi today. Been told it has a fault with start/stop and engine light on but they're getting it fixed for me. I assumed it was probably just an MMI fault or something. The car has only done 50k miles. Thank you greatly for bringing this to my attention.

Other than that, has the car been reliable?

Hope you are getting a good warranty with it but personally I would get something else non-Audi.

[stevemcs]

Have a look at the vag technic video where they ran into this issue after replacing the cams and timing chains.

[JAMSXR]

FMOB said:

Ollie04TT said:

About to put a deposit down on a 21' Q7 55tfsi today. Been told it has a fault with start/stop and engine light on but they're getting it fixed for me. I assumed it was probably just an MMI fault or something. The car has only done 50k miles. Thank you greatly for bringing this to my attention.

Other than that, has the car been reliable?

Hope you are getting a good warranty with it but personally I would get something else non-Audi.

No point in scaremongering. All brands have their (expensive) issues. I’ve just switched from a Honda Type R to an RS4, the Honda was riddled with problems.

[FMOB]

JAMSXR said:

FMOB said:

Ollie04TT said:

About to put a deposit down on a 21' Q7 55tfsi today. Been told it has a fault with start/stop and engine light on but they're getting it fixed for me. I assumed it was probably just an MMI fault or something. The car has only done 50k miles. Thank you greatly for bringing this to my attention.

Other than that, has the car been reliable?

Hope you are getting a good warranty with it but personally I would get something else non-Audi.

No point in scaremongering. All brands have their (expensive) issues. I’ve just switched from a Honda Type R to an RS4, the Honda was riddled with problems.

Not scare mongering at all, my car has the same dash design which is so well known for rattles and squeaks that dealers will just have a go at repairing it without the usual quibbling, mine has been back 3 times in 18 months just for the dash alone.

Audi's legendary build quality used to exist but is a distant memory now.

[ducnick]

Ollie04TT said:

About to put a deposit down on a 21' Q7 55tfsi today. Been told it has a fault with start/stop and engine light on but they're getting it fixed for me. I assumed it was probably just an MMI fault or something. The car has only done 50k miles. Thank you greatly for bringing this to my attention.

Other than that, has the car been reliable?

Apologies for the very slow reply. But…. For me, other than the 48v starter failure the car has been faultless reliable with just yearly servicing + transmission fluid change (not part of the service schedule but required if you want the gearbox to last beyond 100k miles). I’m hanging onto mine despite the well known starter issue. I figure mine lasted 60k miles so the new one might take it to 120k miles at which point I will be looking to move it on. I tried the 55 petrol engine in a newer q7 with the button free interior and personally found the engine unsuited to the type of car, and the interior much cheaper feeling and hard to use while driving, so I am not looking to swap to a newer Audi sadly.
Having said all that, I will be renewing the Audi approved warranty for as many years as they will sell it to me as I think it’s a fairly priced insurance scheme considering the potential costs involved with these type of cars (regardless of brand)