Hello

I am not asking for help, but I thought I would share what resolved an issue on my A6 2015 2L TDI Ultra.

2 years ago, I first got this same issue. My local garage couldn't find any error codes with their ODB reader, a Snapon one I think, so they recommended that I take it to Audi!

Audi told me it was the Adblue pump and after just under £1500 spondoolies later I was back on the road, feeling skint.

Roll on 2 years, I am driving home from Heathrow, wiped out from Jet lag, and 3 miles from home, boom, the same alert pops up.

Audi are booked out for 5 weeks, so I started googling, and decided to go for a VCDS connector from RossTech, which I bought from Gendan Ltd, great service from them.

Connected it up and ran a scan, but nothing specific came up for Adblue issues. It did say that my battery was low on power and failing! Googled a bit more and found low battery voltage can cause these types of no start errors, as the sensors and pump are very voltage sensitive. It also said it can cause other minor issues. I also had a problem where the automatic handbrake wouldn't come one and other niggly things, which I just put down to bugs in Audi software.

So I bought a new battery, used VCDS to code it to the car so BEM would reset, cleared the remaining error codes, reset Adblue modules and took it for a drive. After an hour, the alert was still on the dash. Feeling despondent, I started heading home and 5 mins later, the warning had gone, fault clear and I am good to go. It just needed an extra long drive for the ECU to clear the fault.

So just a heads up, its not always a £700 part to replace, beware of failing batteries, £180 for a new one, phew!

Going to use the VCDS to tweak a few things now like disabling the stop start always on pain in the !Removed! feature.

Thanks Karl for that useful information.

It is worth noting that modern cars are extremely sensitive to the electrical power supply which needs to be stable under all load conditions. Dying batteries can often start the engine normally yet cause a variety of electronic faults such as loss of automatic stop/start function, and false warning messages on the dashboard, amongst others. Even top quality batteries can need to be replaced after five years.