The E63 I now own.

[Dammit]

This auxiliary battery is around six months old- would failing this fast indicate an underlying fault somewhere?

 

[AMGeed]

This auxiliary battery is around six months old- would failing this fast indicate an underlying fault somewhere?

Have you checked the voltage?
Could be low voltage causing the error message.

 

[Dammit]

The voltage of the aux battery? In which case, no.

 

[Will]

I’d be surprised if it were the battery again, but either way it would be under warranty - I don’t think you have to take it back to the same MB dealer, if that helps.

FWIW, MB Guildford are excellent - and fairly priced too. I would recommend giving them a try if you need to take it back in

 

[AMGeed]

The voltage of the aux battery? In which case, no.

That's what I'd be checking before anything else.

 

[st13phil]

This auxiliary battery is around six months old- would failing this fast indicate an underlying fault somewhere?

Hmm.... Unlikely to be the battery then. Diagnostics required...

 

[st13phil]

but either way it would be under warranty

The silver lining

 

[Dammit]

Hmm.... Unlikely to be the battery then. Diagnostics required...

The car stalled when I was waiting at a junction on Sunday, I’m wondering if the two things are related (the aux battery fault had shown on the way there, but not on the way back).

 

[Dammit]

Let’s see if I can post a video

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[AMGeed]

^ Low voltage looking unlikely after viewing video. If there was low voltage on the aux battery the amber ECO light wouldn't be displayed in the cluster. The fact the message displayed says "Stop/Start inactive would lead me to think the problem lies elsewhere.
As Phil suggests, maybe time for Star diagnostics.

 

[Dammit]

It’s booked in for 8am on Thursday morning. Hopefully something can be done quickly as I need the car for the weekend.

 

[Dammit]

Just dropped the car off, service person says that if the fault isn’t the battery then they’ll charge me £120 for running the diagnostic. Which presumably means that if they misdiagnosed it last time and just threw a new battery in without fixing whatever killed the last one then I’ll be on the hook for the diagnostic charge, another battery and fixing the actual problem.
Fingers crossed that Mercedes batteries are total crap I guess.
I also asked them to check that the seats were functioning as expected, but the chap didn’t seem to understand what I was asking them to do so unsure what’s going to happen there.

 

[C43AMG]

Where do you live ? Someone on the Forum must be able to recommended an indie near you !!

They sound like rubbish

 

[Dammit]

I’m using them because there is a parts and labour warranty on the battery, and I don’t have the time to get to (say) MB Guildford in the week.

 

[Dammit]

Looks like I was mistaken- they replaced the starter battery last year, it’s the aux that has gone now. £445.

 

[bolidemichael]

I suppose that the appropriate response is 'dammit'

 

[Dammit]

True. I am almost at the point of needing rear discs and pads- do those nice floating Brembo discs exist for the rear?

 

[st13phil]

Looks like I was mistaken- they replaced the starter battery last year, it’s the aux that has gone now. £445.

Ahhh… that sort of explains it.

That's an eye-watering price for supplying and fitting the aux battery though.

 

[st13phil]

do those nice floating Brembo discs exist for the rear?

AFAIK, no.

 

[Dammit]

Ahhh… that sort of explains it.

That's an eye-watering price for supplying and fitting the aux battery though.

Yes, Mercedes main-dealer pricing makes you feel like you've been abused every single time. Hopefully they won't break something on the car and then deny it this time. I need the car for the upcoming long weekend or I'd have taken it elsewhere for the battery.

I won't be getting Mercedes Benz Bromley to supply and fit the rear discs and pads, put it that way.

If anyone has a recommendation for where to buy the OEM pads and discs (in the sad absence of those nice floating Brembo ones) please do say.