Almost 20,000 2021 Ram Heavy Duty pickup trucks are being recalled due to an issue that could lead to fires in the engine compartment.

Documents recently published by the National Highway Traffic Safety Administration (NHTSA) reveal that 2021 RAM 2500, 3500, 4500, and 5500 models equipped with the automaker’s 6.7-liter turbodiesel inline-six engine have a bad relay in the Solid State Intake Heater Grid.

An investigation from Stellantis following recent fires of 2021 Ram Heavy Duty trucks traced the issue back to this relay. While there have been fires triggered by the problem, the car manufacturer isn’t aware of any injuries related to them.

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Owners of affected vehicles will be informed of the recall starting April 30 through mailed notices. However, the company doesn’t yet have a fix ready for the issue, stating that it is still under development. Whenever the fix is given the green light, repairs will be carried out free of charge.

This isn’t the only safety campaign issued by Ram this year. In February, the carmaker announced a recall for 2021 Ram 1500, stating that the brake clip which retains the master cylinder push rod to the brake pedal could be missing. It noted vehicles without the clip could allow the master cylinder pushrod to disconnect from the brake pedal pin, separating the brake pedal from the brake system.

Moreover, in February a recall was issued for 84,978 Ram 2500 and 3500 models from the 2019 and 2020 model years due to a transmission leak risk.