Paul Hurtt

My 21 Sierra has the opposite problem. The DEF indicator goes to empty intermittently. I get the empty warning, with the speed reduction in “X” number of miles. Service bulletin for DEF software flash done by dealer. Went to empty again after a week. Dealer changed DEF tank. Happened again a month later. GM in Detroit says likely bad DEF tank. I’m awaiting another DEF tank, along with a full day without my truck…

Do you have “ On Star” if so, you can call and ask for a diagnostic report. If there was a code, you can look it up or take it the dealer to read the memory. My 2021 1500 3.0 ( 49K miles) had a check engine light for no apparent reason. Called on star, got the report. Dealer said it was the “ coolant flow control valve” They changed the valve. Warranty item, so other than an inconvenience, no issue.

2021 Elevation, 48K miles. Had a check engine light come on, along with the DEF tank low warning ( repeat problem with DEF system) Dealer checked code, tech said it meant the Engine Coolant Flow Control Valve needed replacing. Only problem is none in stock, and wont be available till after the 1st of the year. Between the multiple trips to the dealer for the DEF system for the DEF system. First fix was to Reflash software according to the SB. Same issue 2 weeks after the software reflash. Dealer replaced the entire DEF tank being after the 4th time it went into a "DEF tank Empty" condition"after software load. 2 weeks after the tank was replaced and filled, another " DEF Tank empty" alert that cleared after about 10 miles. I do not trust the truck. I'm waiting to get stranded somewhere. I get NO consolation that the dealer has sent a synopsis email of my problems to GM Engineering. That was 3 weeks ago. No response from them. The only common item between these two systems and their continued faulting is the ECM. But hey, I'm not an engineer...