Bought a nice 2014 GL350 from an indy dealer - and on the way home the 'check engine' light came on. Took it to my local MB mechanic (not an MB dealer) and after a lot of back and forth found out these sensors are NOT covered under the 8/80k emissions warranty, are NOT covered on the extended warranty I bought.
Nightmare. Local guy here in Ft Myers (top mechanic - very highly regarded) is honest and explained that even if replaced - no guaranty that it won't be the "particulate matter sensor" and "we've never done one of those"
Went to new MB dealer here - they said the same damn thing - and told me it would be $2k just for the 2 NOx sensors
Indy dealer is done with me.
MB USA 'negotiated' a 20% discount with the MB dealer.

Questions: am I hurting the vehicle by driving it? Does any of this NOx stuff really matter to engine performance (I've read blogs that question the whole thing) ???

I've had another mechanic pull the two sensors and clean them. Worked for a few days - back to check engine light...

Anyone got any suggestions on what to do - or not do?

Thanks!

Dan