I have a 2012 chevy 3500 with LML engine. It has recently tripped the Service Emission or milage will be limited on the dash. The Check Engine light came on but there were no DTC stored in the computer. The last time this happened my DEF tank was empty and there were codes present. I have topped off the DEF Tank and that cured the Check Engine light but it still has the Service Emissions on the dash. Any Ideas?

 

My 2014 had a factory notice sent out that says the DEF tank heater had a problem. Free repair if it happens. Mine set the CEL and a reset only lasted a few days. Dealer replaced heater and no more problem. I don't think the Service Emissions light came on, though.