Some units of the 2020 GMC Sierra 1500 pickup truck motivated by the 3.0L LM2 turbo-diesel Duramax engine may have a faulty cylinder 2 glow plug that can cause issues, according to a special coverage bulletin released by The General.
The Check Engine light may come on as a result of the potential failure of the defective glow plug the affected 2020 GMC Sierra 1500 trucks were produced with. This will also generate a specific diagnostic trouble code.
As outlined by Special Coverage bulletin N232430460, service personnel are instructed to check whether a possibly affected 2020 GMC Sierra 1500 has indeed suffered a failure of the glow plug in cylinder 2. Affected trucks will be marked in the Applicable Warranties section found in the GM Global Warranty Management system. Running a diagnostic on the vehicle will also show the known diagnostic trouble code for the problem.
If these steps confirm that a GMC Sierra 1500 is in fact affected by the issue, replacement of the glow plug in cylinder 2 of the Duramax engine should be carried out. This process requires 1 to 1.7 hours, including the diagnostic check. The throttle body gasket must also be replaced.
GM offers reimbursement of “reasonable and customary expenses” to the owner of an affected 2020 GMC Sierra 1500 pickup, provided the repairs are carried out while the vehicle’s powertrain is still under warranty.
Notably, the bulletin is also a notification of extended warranty coverage that applies only to this specific glow plug issue and replacement procedure. The extended coverage starts on January 29th, 2024 and lasts for 15 years or 150,000 miles, whichever comes first. The Duramax engine in the 2020 GMC Sierra 1500 is ordinarily covered by a 5-year or 100,000-mile powertrain warranty.
As a reminder, the LM2 turbodiesel engine is common in The General’s pickup trucks and SUVs, where towing capacity is aided by its significant low-end torque. The 3.0L LM2 develops 277 horsepower at 3,750 rpm and 460 pound-feet of torque at 1,500 rpm. The Chevy Silverado 1500, GMC Sierra 1500, Chevy Tahoe, Chevy Suburban, GMC Yukon, and Cadillac Escalade are all equipped with it as an option in the 2019 through 2021 model years in conjunction with the 10-speed automatic transmission. The Sierra 1500 is built at the GM Fort Wayne plant in Indiana and the GM Silao plant in Mexico.