Ram 2500 diesel fuel filters

The manual's Engine Fluid And Lubricants table for the 6.7L diesel lists:

It says using a fuel filter that does not meet the manufacturer's filtration and water separating requirements can severely impact fuel system life and reliability, and that you must use Mopar/Cummins approved fuel filter elements in both engine mounted filter assemblies. The 6.4L gasoline engine's Maintenance Plan has no fuel filter replacement item; this guide covers the diesel.

From the 2026 Ram 2500/3500 owner's manual (Engine Fluid And Lubricants, 6.7L Diesel; Fuel Water Separation; Draining Fuel/Water Separator Filter), read November 8, 2026.

How often to change Ram 2500 fuel filters

The Maintenance Plan for the 6.7L diesel engine lists Replace the front engine fuel filter and Replace the rear engine fuel filter at every 15,000-mile column (15,000, 30,000, 45,000 miles and so on to 150,000), which corresponds to every 24,000 km or 12 months, whichever comes first. The same plan lists an engine oil change every 15,000 miles (24,000 km) or 12 months or 500 hours, or sooner if prompted by the oil change indicator system.

From the 2026 Ram 2500/3500 owner's manual (Maintenance Plan, 6.7L Diesel Engine), read November 8, 2026.

Water In Fuel Indicator Light

If water is detected in the water separator while the engine is running or the ignition is ON, the Water In Fuel Indicator Light will illuminate and an audible chime will be heard five times. The manual says to stop the engine and drain the water from both filters. If the light remains on, do not start the engine before you drain water from the fuel filters, to avoid engine damage.

If the light comes on with a single chime while you are driving or with the ignition ON, there may be a problem with the water separator wiring or sensor; the manual says to see an authorized dealer for service.

From the 2026 Ram 2500/3500 owner's manual (Draining Fuel/Water Separator Filter, Diesel Engine), read November 8, 2026.

How to drain water from the fuel filters

The best access to the water drain valves is from under the hood. Do not drain the filters when the engine is running, and drain into an appropriate container, because diesel fuel will damage blacktop paving. The manual's steps are: within 10 minutes of vehicle shutdown, turn the engine mounted filter drain valves (on the side of the filter assembly) counterclockwise 1/4 turn, turn the ignition to ON, and leave the drain valve open until all water and contaminants have been removed. When clean fuel is visible, close the valve:

1. Rotate the 1/4 turn drain valves fully clockwise to their stops.
2. Continue turning the drain 1/2 of a turn to properly compress the seal.
3. Turn the ignition switch to OFF.

From the 2026 Ram 2500/3500 owner's manual (Draining Fuel/Water Separator Filter, Diesel Engine), read November 8, 2026. Over-tightening the drain over-compresses the seal, which will damage it, cause a leak and require the entire sensor to be replaced. After proper draining the light stays on for about 10 seconds, or about three minutes if the water was drained with the engine running.

How to replace the Ram 2500 fuel filters

The manual's steps for replacing the engine mounted fuel filters are:

1. Ensure the engine is turned off.
2. Place a drain pan under the fuel filter drain hoses.
3. Open the water drain valves a quarter turn counterclockwise and completely drain fuel and water into the approved container.
4. Close the water drain valves.
5. Remove one lid using a socket or strap wrench, rotating counterclockwise. Remove the used o-ring and discard it.
6. Remove the used filter cartridge from the housing and dispose of it according to your local regulations.
7. Wipe clean the sealing surfaces of the lid and housing.
8. Install a new o-ring into the ring groove on the filter housing and lubricate it with clean engine oil.
9. Remove the new filter cartridge from its plastic bag and install it into the housing.
10. Push down on the cartridge to make sure it is properly seated. Do not pre-fill the filter housing with fuel.
11. Install the lid onto the housing and tighten it to 22.5 ft-lb (30.5 Nm). Do not overtighten the lid.
12. Repeat steps 5 through 11 for the second engine mounted fuel filter.
13. Prime the engine, then start the engine and confirm there are no leaks.

From the 2026 Ram 2500/3500 owner's manual (Engine Mounted Fuel Filter Replacement, Diesel Engine), read November 8, 2026. The manual says to install the filter dry and let the in-tank lift pump prime the fuel system, because pre-filling could introduce debris.

Priming if the engine has run out of fuel

The manual warns not to open the high pressure fuel system with the engine running. Its priming steps are:

1. Add a substantial amount of fuel to the tank, approximately 2 to 5 gal (8 L to 19 L).
2. Complete three priming cycles: turn the ignition to RUN and wait approximately 30 seconds, which activates the in-tank fuel pump, then turn it off and leave it off for at least 30 seconds. Repeat three times before cranking the engine.
3. Start the engine using the Normal Starting procedure.
4. Once the engine starts, let it idle for a minimum of 30 seconds.

From the 2026 Ram 2500/3500 owner's manual (Priming If The Engine Has Run Out Of Fuel, Diesel Engine), read November 8, 2026. Do not engage the starter for more than 15 seconds at a time, and allow two minutes between cranking intervals. The engine may run rough until the air is forced from the fuel lines.

Biodiesel and fuel blending

A maximum blend of 20% biodiesel meeting ASTM D-7467 may be used in the Cummins diesel. The manual says biodiesel above 20% can negatively impact the fuel filter's ability to separate water from the fuel, resulting in high pressure fuel system corrosion or damage, and that ethanol blends are not recommended or approved.

Do not use alcohol or gasoline as a fuel blending agent. The manual also says commercially available fuel additives are not necessary for proper operation of the Cummins diesel engine.

From the 2026 Ram 2500/3500 owner's manual (Priming notes; Biodiesel Fuel Requirements), read November 8, 2026.

Ram 2500 service at Elgin CDJR

If your Ram 2500 diesel is due for fuel filters or the Water In Fuel light is on, our Ram service center can help. Our service department is open Monday to Friday 7 a.m. to 7 p.m. and Saturday 7:30 a.m. to 4 p.m., and is closed Sunday. Elgin CDJR is at 1500 W. Lake St. in Streamwood. Get directions.