Hi folks,

Looking for some advice to see if anyone has dealt with this before. I bought my first Audi around 8 months ago and, after a few weeks, noticed that on start‑up the coil light would stay on and flash. Whenever this happened I first noticed all electric windows stopped working. Over the months I’d been clearing some faults with an OBDII scanner, often seeing glow plug errors for cylinders 1, 2 and 4. After clearing them, the car would usually behave normally again once it had been sitting off for a short while.

Recently the issue has become constant. The OBD scanner no longer seems to clear anything related to this fault, and I’m not sure it ever truly did. For the past 2–3 weeks the coil light flashes on every start, none of the windows have power, start/stop is also disabling due to a system fault, and “SAFE” appears above the mileage.

Mechanically the car drives fine with no limp mode. I’ve narrowed it down to a few possibilities:

1. CCM fault – possibly water logged module found under passenger footwell (not yet checked)
2. Weak/failing battery – unstable voltage (seems less likely, though the car does struggle to start after sitting for a few days)
3. Bad earth/ground connection

All fuses check out fine, and there’s no dimming of interior lights when trying the windows – they simply have no power. I’ve heard this can be a common issue on older A3s.

For reference, it’s a 2011 Audi A3 2.0 TDI Quattro.

If anyone has experienced something similar, I’d really appreciate pointers on what to check next or what fixed it for you.

Thanks for taking the time to read. I’ll keep an eye on replies and get back to anyone ASAP.

Lee

Welcome Lee,

It might be getting over repetitive, but a quick forum search will always point to first eliminating battery efficiency before considering any other more complex possibilities. 

Battery efficiency checking is usually free ( Halfords stores normally do this). 

If found to be to be sub standard, you would do your wallet a favour by coming back to us before committing to buy. 

Please let us know how you get on.

Regards,

Gareth. 

Morning, thank you. I didn’t even know Halfords done this for free, will look at this today! 

Booked in for battery check, will feedback on outcome.

Battery check carried out at local Kwik Fit, guys there said it failed but I didn’t get any notes of volts etc.. looking at getting the battery replaced and will check back in.

What brand of battery are you considering, and where are you going to get that fitted? 

I was just going to pick this one up from Halfords and fit it myself: Halfords AGM096 Start/Stop 12V Car Battery (5 Year Guarantee)

£150 ish for a Halfords branded battery?
Who now manufactures Halfords batteries? - don’t know. 
 

Worth thinking about its equivalent Exide from Parts in Motion EBay - delivered to your door for a discounted £94 ish until 16/2 ? 

Will check this out, thanks!