A fix is newly available for specific units of the 2024 GMC Sierra HD truck, which may be affected by the engine block heater cord not being fully and correctly seated. A GM service update provides details of the remedy now offered through dealer service. This issue only applies to the refreshed 2024 model year of the truck.
The issue applies explicitly to the 6.6L V8 L5PÂ turbodiesel Duramax engine developing 470 horsepower and 975 pound-feet of torque, which is an available option for the 2024 GMC Sierra HD, as GM service update number N232433290 describes. It applies to both 2500HD and 3500HD models equipped with this engine. 
The available fix is offered for GMC Sierra HD pickups brought to the dealership for any reason. Dealerships are also instructed to apply the remedy to affected Sierra trucks in their current inventory. Before beginning the fix, the GM Global Warranty Management system should be consulted to see if the specific vehicle is marked “Open” on its Investigate Vehicle History page.
To remedy the issue, dealership mechanics should inspect the engine block heater cord to see if it is fully seated. This inspection will require the removal of the truck’s front passenger-side wheel. If the cord is not fully seated, the dealer should reinstall it and its retention clip. No replacement parts are needed to complete this repair, though the cord coupling should be treated with dielectric grease, which keeps moisture out of electrical components, before reinstallation.
GM offers the fix throughout the New Vehicle Limited Warranty period of affected GMC Sierra HD units.
As a reminder, the 2024 GMC Sierra HD debuts several changes and updates, including a new front bumper and front fascia, along with half a dozen new exterior colors. The luxurious 2024 GMC Sierra HD Denali Ultimate, set apart by its Vader chrome exterior trim, 20-inch Ultra-bright wheels, and Alpine Umber interior, has joined the trim lineup. The refresh also launched the GMC Sierra HD AT4X, featuring a suite of rugged off-road upgrades for superior off-road performance. It also delivers many of the premium features that come with the Denali trim.
The GMC Sierra HD uses the GM T1 platform for structure, while the truck is produced at the GM Flint plant in Michigan.
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Comment
What a joke with these heater cords. My 2018 2500hd has been recalled a few times for what appears to be a similar issue. First the recall was to cut the cord , second recall was to have a new one installed, third was to come back and cut the cord again.
Sure glad I never had the first one done. Besides, with climate change its getting warmer by the minute, who needs it anyway.