There are 8 owner-reported engine complaints for the 2021 Ram 3500in NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
The contact owns a 2021 Ram 3500. The contact received notification of NHTSA Campaign Number: 25V552000 (Back Over Prevention) and 25V720000 (Engine and Engine Cooling); however, the part to do the recall repair was not yet available. The local dealer was contacted. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the issue. The contact had not experienced a failure.
The contact filed the complaint on behalf of the customer, who was the owner of a 2021 Ram 3500. The contact stated that while the owner was driving at an undisclosed speed, the vehicle caught on fire. No warning lights were illuminated. The owner informed the contact that the fire came from the engine bay. The fire department arrived and extinguished the fire. A police report was filed. The vehicle was taken to a local tow yard. The vehicle was later towed to the independent mechanic. No injuries were sustained. In addition, the contact stated that the transmission was replaced by an independent mechanic. The failure occurred the following day after the vehicle was released by the independent mechanic. In addition, the owner of the vehicle had received a recall notification NHTSA Campaign Number: 23V060000 (Electrical System). The manufacturer was not made aware of the failure. The failure mileage was approximately 99,000.
Failure of hydraulic lifters and camshaft in Cummins 6.7 liter diesel engine of 2021 RAM 3500. Engine exhibited significant ticking noise and the engine does not work properly, putting the safety of driver and passengers in vehicle at risk. Vehicle is not driveable. This issue has been confirmed by the RAM dealership in Livingston, Montana. The 2021 RAM 3500 truck has been sitting at the RAM dealership for the past seven weeks awaiting parts and a fix that RAM trucks is still trying to figure out. Apparently, this has become a common problem with the RAM Cummins 6.7 liter diesels from model years 2019 through current 2025 models, including 2021. The RAM dealership in Livingston, Montana has five separate RAM Cummins 6.7 liter diesel trucks with the same issue awaiting parts and a fix from RAM.
Hydraulic roller lifter failure.
The contact owns a 2021 Ram 3500. The contact stated while driving at an undisclosed speed, the engine temperature gauge became extremely elevated. The contact pulled over to the side of the road and an independent mechanic briefly inspected the vehicle and informed the contact to refill the coolant reservoir. The contact refilled the reservoir and after driving for approximately thirteen minutes, the failure reoccurred. The vehicle was towed to an independent mechanic where it was diagnosed that the EGR cooler and EGR valve needed to be replaced. The vehicle was not repaired. The contact related the failure with Emissions Recall: VB6 (Diesel Engine Calibration); however, the vehicle was not included. The manufacturer was not made aware of the failure. The failure mileage was approximately 190,000.
There exist a defect which is common through multiple years with RAM that have the Cummins 6.7L diesel engine. The problem is the heater bolt in intake system. When this fails it falls into intake and proceeds into piston which requires engine rebuild. Unfortunately the same part is put back in causing repeat. Solution Banks Monster Ram Intake system. Many, many owners over years have experienced loss of vehicle in both new and older models. Engine lock up can cause loss of steering and worse on highways.
Catastrophic lifter failure. Was able to safely deliver vehicle to dealership service department. If not handled properly, engine failure could occur while driving and hurt/kill someone.
See attached document from complainant
Complaints are unverified consumer reports submitted to NHTSA. A high complaint count may reflect vehicle popularity, not defect severity. Data sourced from NHTSA public records.
Data synced from NHTSA on Apr 26, 2026