GM is recalling hundreds of thousands of its HD pickup trucks due to an issue with the optional block heater feature. The automaker says that it can short-circuit and cause a fire in rare circumstances.

General Motors received 122 complaints between December 3, 2019 and May 28, 2021, along with 24 reports of potential fires. The affected vehicles number 331, 274 and include the following trucks equipped with the 6.6-liter Duramax diesel engine and engine block heating cord:

• 2017-2019 Chevrolet Silverado 2500 and 3500
• 2017-2019 GMC Sierra 2500 and 3500

If you’re thinking that these trucks were already recalled for a similar issue, you’d be right. General Motors’ internal investigation revealed that the vehicles affected were involved in recall number 19V328. The automaker notes that vehicles involved in that recall will be closed and addressed under this new recall campaign.

If you own one of those trucks, the condition carries specific indicators that you need to be aware of. From the NHTSA recall document, your vehicle may be affected if you notice “smoke or a burning smell; poor block-heater performance; tripped circuit breakers or blown vehicle fuses; damage to the block heater, the heater cable or engine components; and block-heater coolant pooling under the vehicle.”

The recall states that the cause of the problem relates to a short-circuit condition that can occur if the block heater develops a coolant leak and the coolant contacts the heater’s cable terminal while it is plugged into an energy source. The short-circuit condition can damage engine components and start a fire.

Dealer notifications under the recall are expected to begin on July 1, 2021 and owner notification is scheduled to begin on August 16, 2021. A potential solution is being developed that may include disabling the feature. Owners of vehicles with the feature already disabled will be contacted and offered replacement block heaters and heater cords under a separate customer satisfaction program.