GM recalls Silverado and Sierra HD diesels again for block-heater issue

July 15, 2021

GM is recalling Chevrolet Silverado and GMC Sierra Heavy Duty trucks equipped with a Duramax diesel engine and an optional engine-block heater. A short circuit in the connection to the block heater could cause a fire, the NHTSA disclosed this week.

The short circuit can cause a fire if the block heater's coolant leaks onto the cable terminals while the block heater is plugged in. Customers may notice five indicators of a block-heater problem: smoke or a burning smell; weak or poor performance from the block heater; tripped circuits or blown fuses; damage to the block heater, heater cord, or engine components; or block-heater coolant leaking or pooling under the truck. One owner noticed sparking under the hood when the block heater was plugged in. 

The recall spans the 2017-2019 model years of Chevy Silverado 2500/3500HD and GMC Sierra 2500/3500HD, but only those equipped with a Duramax diesel 6.6-liter V-8 and an engine heater power cord. Heavy Duty GM trucks without the block heater and without the diesel are not affected. The recall encompasses 208,546 Chevy Silverado 2500HD and 122,728 GMC Sierra 2500HD trucks. 

Some of these trucks had been recalled already for a similar issue that GM labeled recall 19V328. The recall remedy didn't work. Upon further investigation, GM received 122 complaints and 24 reports of potential fires in a 16-month period between December 2019 and May 2021 after those vehicles had been repaired. 

The next remedy may be to disable the feature, GM reported in filings with the NHTSA. Vehicles that have already been recalled and repaired will have the block heater disabled and owners will be offered replacement block heaters and power cords. Dealers will conduct the swap free of charge, and GM will reimburse owners who have had the work done already. GM is still figuring out the best remedy, but in the meantime, owners will be notified of the possible replacement block heaters as early as August 16. 


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