Duramax and Blue Def
I had to replace both nox sensors at around 40,000 miles. They were covered under warranty. The GM dealer asked what def fluid I was using. Had been using Blue Def from Walmart, he said that Blue def ...
Forum Discussion
99.99% of the time on 2011 GM trucks the "Poor Quality DEF" message is due to faulty NOx sensor and not actually the quality of the DEF. There are countless reports of this over on the Dmax forum. Later model years can also happen but they seem to be in much smaller numbers.
