I'm sure this has been discussed somewhere before, so please forgive me. I bought a 2015 VW Jetta Diesel SEL TDI a couple of months ago and just recently - because of the warning on my dashboard - became aware of the need of AdBlue and the importance of adding it to the car. I eventually added more (2.5 gallons) when the warning got down to 500 miles (about a week ago) but the warning system recently came back on saying that I am down to 55 miles before my engine won't start. Could there be a fault with a sensor somewhere? Or could it be that I bought a store- brand product?
Any help is greatly appreciated.