One problem related to exhaust system emission control urea injection system (def) has been reported for the 2020 GMC Sierra 3500. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2020 GMC Sierra 3500 based on all problems reported for the 2020 Sierra 3500.
Diesel exhaust fluid tank heater malfunctioned and meted tank and connectors.
| Engine And Engine Cooling problems | |
| Exhaust System Emission Control Urea Injection System (def) problems |