The car is 1.5kmi out of the warranty. CEL is for DEF fill level sensor. Technically the whole active DEF tank should be replaced, because sensor is built-in to it. Dealer wants ~$1300-$1400 for this (parts and labor). I believe it is a part of the same problem I did have in July (look below) I did have similar CEL coming on in July (while the car was under the warranty). I clearly remember, that then SA told me, that sensor is giving the results out of range, but on the papers is shown, that they replaced the DEF injection valve (or something like that), and nothing is said about the sensor. I got couple questions now: 1) Is it possible to force the dealer to replace the tank under the warranty 2) Does anybody know where is the fill level located in the DEF tank and what wires pigtale is coming to it?