The 2021 Ram 3500 with the 6.7L Cummins is a workhorse, but early CP4.2 fuel pump failures and emissions system issues plague even low-mileage examples. When they go catastrophic, you're looking at engine-out repairs that dwarf typical diesel maintenance costs.
CP4.2 Fuel Pump Catastrophic Failure
Occasional · high severity
Typical onset: 30,000-80,000 mi
Symptoms: Hard start or no-start condition suddenly, Metal shavings in fuel filter, Loss of fuel pressure with no warning, Entire fuel system contaminated with metal debris when pump grenades
Fix: When the CP4.2 fails internally, metal contaminates the entire fuel system. You're replacing pump, all injectors, fuel lines, tank cleaning, sometimes even the lift pump. Expect 20-30 labor hours for complete remediation. Many owners pre-emptively install CP3 conversion kits or add fuel filtration systems.
Estimated cost: $8,000-15,000
DEF/SCR System Failures (NOx Sensor, DEF Heater, Injector)
Common · medium severity
Typical onset: 60,000-120,000 mi
Symptoms: Check engine light with NOx sensor codes, DEF system warning, reduced power mode imminent, DEF heater grid failure in cold climates, DEF injector crystallization causing dosing errors
Fix: NOx sensors are 2-3 hours each to replace. DEF heater assembly is 4-6 hours. DEF injector requires exhaust work, 5-7 hours. Use OEM DEF only and keep the system exercised in winter to minimize crystallization issues.
Estimated cost: $800-2,500
Transmission Oil Cooler Leaks (68RFE)
Common · medium severity
Typical onset: 50,000-90,000 mi
Symptoms: Transmission fluid dripping from radiator area, Low trans fluid level on dipstick, Pink residue on driveway or cooler lines, Overheating transmission under load if fluid low
Fix: Cooler itself or hard lines crack from vibration and thermal cycling. Cooler replacement is 3-4 hours, includes flush and refill. If coolant cross-contaminates trans fluid (rare but catastrophic), you're rebuilding the trans. Inspect lines during every fluid service.
Estimated cost: $600-1,200
EGR Cooler Failure and Clogging
Occasional · high severity
Typical onset: 80,000-150,000 mi
Symptoms: White smoke on startup, Coolant loss with no external leaks, Check engine light for EGR flow codes, Rough idle or misfires when cooler cracks internally
Fix: EGR cooler can crack and dump coolant into intake or clog from soot buildup. Replacement is 8-12 hours (cab-on), involves coolant system work and sometimes intake manifold cleaning. Deleting EGR voids warranty and is federally illegal, but many commercial operators do it to avoid repeat failures.
Estimated cost: $2,000-3,500
Turbocharger Actuator and VGT Mechanism Issues
Occasional · medium severity
Typical onset: 100,000-180,000 mi
Symptoms: Limp mode with underboost codes, Turbo whistle changes pitch or becomes erratic, Poor throttle response and black smoke under load, VGT vanes sticking from carbon buildup
Fix: Electronic actuator fails or VGT vanes seize from soot. Actuator replacement alone is 2-3 hours. Full turbo rebuild or replacement is 6-8 hours. Regular highway driving and quality oil reduce carbon fouling. Some techs try cleaning vanes in place, but results are hit-or-miss.
Symptoms: Sudden catastrophic knocking noise, Metal shavings in oil filter or pan, Loss of oil pressure, Often traced back to CP4 pump failure contaminating oil or missed oil changes
Fix: When CP4 pump shrapnel gets into the oil or oil service is neglected, bearings spin and pistons can crack. Engine-out rebuild: 40-60 hours for short block, pistons, bearings, rings, head gaskets. Many owners opt for reman long blocks due to labor costs being same either way.
Estimated cost: $15,000-25,000
Owner tips
Install aftermarket fuel filtration (like AirDog or FASS) to catch CP4 debris before it kills injectors—cheap insurance at $800-1,500.
Use only Top Tier diesel and OEM-spec DEF; off-brand DEF causes injector crystallization.
Change oil at 5,000-7,500 mi intervals max, even though Stellantis says 15k—Cummins bearings are unforgiving.
Inspect transmission cooler lines and DEF system during every service; early catch saves thousands.
Keep fuel tank above 1/4 to prevent lift pump cavitation and CP4 starvation under heavy load.
Buy a 2021 Ram 3500 if you need the towing capacity and can budget $2k/year for diesel-specific repairs—but verify CP4 pump health and consider a fuel system warranty or aftermarket pump swap immediately.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.
Chrysler (FCA US, LLC) is recalling certain 2021-2022 Ram 1500, Ram 2500, Ram 3500, Ram 4500, and Ram 5500 vehicles. The steering column control module may cause the driver's side air bag not to deploy as intended. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 208, "Occupant Crash Protection."
Consequence: A driver's side air bag that does not deploy as intended increases the risk of injury in a crash.
Remedy: Dealers will replace the steering column control module, free of charge. Owner notification letters were mailed beginning December 11, 2025. Owners may contact Chrysler customer service at 800-853-1403. Chrysler's number for this recall is 14C. Vehicle Identification Numbers (VINs) involved in this recall became searchable on NHTSA.gov beginning November 13, 2025.
Chrysler (FCA US, LLC) is recalling certain 2021-2023 Ram 2500, 3500, 3500 Cab Chassis, and 4500, 5500 Cab Chassis vehicles equipped with a Cummins 6.7L Turbo Diesel engine. An electrical short may occur in the heater grid relay with the ignition on or off.
Consequence: An electrical short in the relay can result in an engine compartment fire with the ignition on or off, increasing the risk of injury.
Remedy: Owners are advised to park outside and away from structures until the recall repair is complete. Dealers will replace the relay, free of charge. This will be a Phased campaign. Phase 1 will include 2023 model year vehicles. FCA US will notify dealers on or about 3/23/2023 and begin notifying owners on or about 4/5/2023. Phase 2 will include 2022 model year vehicles and Phase 3 will include 2021 model year vehicles. FCA US will notify dealers and owners on or about 4/27/2023 for Phase 2 and 5/11/2023 for Phase 3. Interim owner notification letters informing owners of the safety risk were mailed March 28, 2023. Owner notification letters are expected to be mailed April 5, 2023. Owners may contact FCA US, LLC customer service at 1-800-853-1403. FCA US, LLC's number for this recall is 13A. This recall is an expansion of and supersedes recall number 21V-798.
STRUCTURE:BODY:TAILGATE:HINGE AND ATTACHMENTS · 22V904000
2022-12-08
Chrysler (FCA US, LLC) is recalling certain 2019-2022 Ram 1500, 2500, and 3500 pickup trucks. The tailgate may not latch properly due to misaligned tailgate strikers, which could result in the tailgate opening while driving.
Consequence: An unintended tailgate opening while driving may result in a loss of unsecured cargo, possibly creating a road hazard and increasing the risk of a crash.
Remedy: Dealers will inspect the tailgate striker alignment to the box latch and adjust, if necessary, free of charge. Owner notification letters were mailed December 22, 2022. Owners may contact FCA US, LLC customer service at 1-800-853-1403. FCA US, LLC's number for this recall is ZB8.
POWER TRAIN:AUTOMATIC TRANSMISSION · 22V835000
2022-11-10
FCA US, LLC (Chrysler) is recalling certain 2020-2023 Ram 2500 and 2020-2022 Ram 3500 vehicles. A build-up of pressure and heat inside the transmission may result in a transmission fluid leak from the dipstick tube.
Consequence: Leaking transmission fluid may contact an ignition source within the engine compartment, increasing the risk of a fire.
Remedy: Dealers will replace the transmission dipstick and transmission vent assembly, free of charge. Owner notification letters were mailed December 29, 2022. Owners may contact FCA US, LLC customer service at 1-800-853-1403. Chrysler's number for this recall is ZA3.
SERVICE BRAKES, HYDRAULIC:ANTILOCK/TRACTION CONTROL/ELECTRONIC LIMITED SLIP:CONTROL UNIT/MODULE · 22V140000
2022-03-10
Chrysler (FCA US, LLC) is recalling certain 2019-2022 Ram 2500 and 2021-2022 Dodge Durango vehicles, and 2019-2022 3500 cab chassis with GVWR less than 10,000 lbs. The ABS control module software may prevent the electronic stability control (ESC) malfunction indicator light from illuminating during certain conditions. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 126, "Electronic Stability Control Systems."
Consequence: An ESC malfunction indicator light that fails to illuminate during an electronic stability control problem can increase the risk of a crash.
Remedy: Dealers will update the ABS control module software, free of charge. Owner notification letters were mailed March 29, 2022. Owners may contact FCA US, LLC customer service at 1-800-853-1403. FCA US, LLC's number for this recall is Z20.
AIR BAGS:SIDE/WINDOW:CURTAIN · 21V925000
2021-11-24
Chrysler (FCA US, LLC) is recalling certain 2021-2022 Ram 2500, Ram 3500, and 2021 Ram 1500 Classic pickup trucks. The side air bag inflatable curtain (SABIC) assemblies may have been manufactured with the incorrect amount of compressed gas, which can result in an improper air bag deployment.
Consequence: An air bag that deploys improperly can increase the risk of injury in a crash.
Remedy: Dealers will replace the SABIC assemblies, free of charge. Owner notification letters were mailed January 17, 2022. Owners may contact FCA US, LLC customer service at 1-800-853-1403. FCA US, LLC's number for this recall is Y99.
Chrysler (FCA US, LLC) is recalling certain 2021-2022 Ram 3500, 2500 pickup trucks, and Ram 3500, 4500, and 5500 cab chassis vehicles equipped with Cummins 6.7L Turbo Diesel engines. An electrical short in the relay may cause a vehicle fire with the ignition on or off.
Consequence: A vehicle fire increases the risk of injury.
Remedy: Owners are advised to park these vehicles outside of buildings or structures, and not near other vehicles, until the vehicle has been remedied. Dealers will inspect and, if needed, replace the Solid State Intake Heater Grid Relay ("Relay"); if FCA US Recall ID Y08 (NHTSA Recall ID 21V-163) is open, then insulating material will be applied to the Relay after inspection. Owner notification letters were mailed November 10, 2021. Owners may contact FCA US, LLC customer service at 1-800-853-1403. FCA US, LLC's number for this recall is Y76. This recall has been superseded by 23V060.
WHEELS:LUGS/NUTS/BOLTS/STUDS · 21V398000
2021-05-27
Chrysler (FCA US, LLC) is recalling certain 2012-2021 RAM 3500, 3500 Cab Chassis, 4500 Cab Chassis, and 5500 Cab Chassis vehicles. Incorrect information in the Service and Owner's Manuals may cause the flanged lug nuts to be over-tightened, which could result in a broken wheel stud and possible wheel separation.
Consequence: Wheel separation can cause a vehicle crash.
Remedy: Dealers will update the torque specification in the owner's manual and other published service documents. Dealers will also inspect the vehicle's wheel studs, replacing them if necessary, free of charge. Owner notification letters were mailed on November 30, 2021. Campaign Y36 owner notification letters were mailed on November 30, 2021. Campaign Y26 owner notification letters were mailed on December 1, 2021. Owners may contact FCA US customer service at 1-800-853-1403. FCA US's numbers for this recall are Y26 and Y36.
ELECTRICAL SYSTEM · 21V163000
2021-03-11
Chrysler (FCA US, LLC) is recalling certain 2021 Ram 2500, 3500, and 3500, 4500, and 5500 Cab Chassis vehicles equipped with a Cummins 6.7L Turbo Diesel engine. An electrical short may occur in the Solid State Intake Heater Grid Relay, which could result in a vehicle fire.
Consequence: A vehicle fire increases the risk of injury.
Remedy: Dealers will inspect and, if needed, replace the Solid State Intake Heater Grid Relay ("Relay"); if FCA US Recall ID Y08 (NHTSA Recall ID 21V-163) is open, then insulating material will be applied to the Relay after inspection. Customers are advised to not park these vehicles inside of buildings or structures, or near other vehicles until the vehicle has the final repair completed. Owner notification letters were mailed November 10, 2021. Owners may contact FCA US, LLC customer service at 1-800-853-1403. FCA US, LLC's number for this recall is Y76. Owners may contact FCA US LLC customer service at 1-800-853-1403. FCA US LLC's number for this recall is Y08. This recall has been superseded by recall number 21V-798.
Vehicle Info — 2021 Ram 3500
Performance
Horsepower
370hp
Torque
850lb-ft
0–60 mph
7.8sec
Quarter mile
15.9sec
Top speed
100mph
Capability & size
Towing capacity
37,100lb
Payload
7,680lb
Curb weight
7,450lb
Wiper blades
Pickup truck, no rear wiper. Both blades are same length on this generation.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2021 Ram 3500 6.7L I6 Cummins Diesel and can vary by trim.
🔧 Built by master technician Chris Hackleman · Master Technician · 20+ years.