Hi all. A few months ago my Add Blue warning light came on (A4 Avant, 2016) Diagnostics showed a complete system failure and a bill approaching £3k. I left the dealer and went to my local trusted garage. He agreed with the diagnostics and suggested a cheaper solution. Completely bypass the AB system and flash the computer system to tell it there is no more AB. This cost around £500. 

Everything is fine except before, on a long trip driving at a steady 65, I could get an average in the high 70's per gallon, even 80mpg. Now doing the same journey the best I could do was 64 mpg? Same load, similar weather, tire pressures all correct. I understood that AB had nothing to do with economy and was only for emissions.  

 

Sounds like it's had a remap too. 

£500 just to map out the AB system is alot.

I had the same thing done on a Seat Alhambra 2015 for €200 a while ago. And it didnt have any effect on the MPG of the car.

I would be going back to the people that mapped out the AB system and ask them exactly what else they done at the same time.

I know costs are going to be different between different places etc, but i dont see why you would be paying more than double the price it cost me here in ireland.