I took my 2011 Duramax to the Chevy dealer recently with the DEF fluid quality poor error message and the check engine light on. When I picked it up the dealer asked me where I bought my DEF. I told him it was the Peak brand from Wal-Mart. He said that I needed to buy it from somebody else cause the sample they tested did not pass. Just wondered if others had this same problem. They replaced the DEF, cleared the codes and did a regen. So far so good.
