Exhaust System Emission Control Urea Injection System (def) Problems of GMC Sierra 1500

GMC Sierra 1500 owners have reported 3 problems related to exhaust system emission control urea injection system (def) (under the engine and engine cooling category). The most recently reported issues are listed below. Also please check out the statistics and reliability analysis of GMC Sierra 1500 based on all problems reported for the Sierra 1500.

1 Exhaust System Emission Control Urea Injection System (def) problem of the 2020 GMC Sierra 1500

Failure Date: 03/18/2026

The contact owns a 2020 GMC Sierra 1500. The contact stated that while starting the vehicle, the engine hesitated while turning over. The vehicle started with the check engine warning light illuminated, and the def (diesel exhaust fluid) sensor light was illuminated. The message “94 miles before vehicle enters limp mode" was displayed and instructed the contact to see the diesel exhaust fluid section of the owner's manual. The vehicle was restricted to a 65 mph max speed. The vehicle was towed to a dealer, where it was diagnosed, and it was determined that the def tank pump assembly had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was 121,000.

See all problems of the 2020 GMC Sierra 1500 🔎.

2 Exhaust System Emission Control Urea Injection System (def) problem of the 2024 GMC Sierra 1500

Failure Date: 03/18/2026

The contact owns a 2024 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the fuel level indicator on the instrument panel became inoperable and provided incorrect information. The contact stated that due to the inaccurate fuel level, the vehicle almost went into limp mode with the message “refuel - empty now” displayed. The vehicle was taken to the dealer, where it was diagnosed, and determined that the def tank had failed and needed to be replaced. The vehicle was not repaired. The contact was informed by the dealer that parts to repair the vehicle were on backorder. The manufacturer was made aware of the failure. The failure mileage was approximately 34,895.

See all problems of the 2024 GMC Sierra 1500 🔎.

3 Exhaust System Emission Control Urea Injection System (def) problem of the 2020 GMC Sierra 1500

Failure Date: 01/24/2026

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at 65 mph, the def tank failed. The vehicle went into three phases of limp mode and the vehicle unexpectedly decelerated while driving. The def system service message was displayed. The vehicle was taken to the local dealer, where it was diagnosed with def tank failure, and the tank needed to be replaced, even though the tank was full. The part was on backorder for several weeks. The contact was not provided with a loaner. The vehicle was repaired. The manufacturer was contacted and opened a case, but no additional assistance was provided. The failure mileage was approximately 70,000.




Sierra 1500 Service Bulletins
Sierra 1500 Safety Recalls
Sierra 1500 Defect Investigations