Where Is the 68436631AA Filter Located? Complete 2019-2024 RAM 6.7L Cummins DIY Guide

Where Is the 68436631AA Filter Located? Complete 2019-2024 RAM 6.7L Cummins DIY Guide

If you bought a 2019-2024 RAM 2500, 3500, 4500, or 5500 with the 6.7L Cummins and went looking for your fuel/water separator under the hood, you probably came back confused. It's not there. The mopar 68436631AA is mounted to the chassis rail under the truck, not on the engine — and that's the single biggest source of confusion for owners doing their first fuel filter service on the new platform.

This guide covers exactly where to find the 68436631AA, how to replace it without breaking anything, and how it pairs with the engine-mounted mopar 68157291AA fuel filter to protect your CP4.2 high-pressure pump.

What Changed in 2019 (And Why Owners Get Confused)

For the 2019 model year, RAM redesigned the entire 6.7L Cummins fuel filtration system to support the new CP4.2 high-pressure injection pump. The old single-stage layout used the 68197867AB chassis filter. The new layout replaced it with the 68436631AA — a more aggressive water separator with updated mounting and connection geometry.

This means mopar fitment is strict here:

  • 2013-2018 RAM 6.7L → uses 68197867AB
  • 2019-2024 RAM 6.7L → uses 68436631AA (NOT interchangeable)

If you order the wrong one, the threads, mounting bracket, and fuel line fittings won't match. Always confirm your model year before clicking buy.

Where Is the 68436631AA Located?

On 2019-2024 RAM 2500 through 5500 trucks:

  • Position: Driver-side frame rail, roughly under the driver's seat
  • Mounted to: A bracket bolted to the chassis (frame-mounted, not engine-mounted)
  • Visible from: Underneath the truck — you'll need to crawl under or use a low ramp

It looks like a tall canister filter with two fuel lines, an electrical connector for the water-in-fuel sensor, and a drain valve at the bottom. The water-in-fuel sensor screws into the bottom housing and gets transferred to the new filter during replacement.

Tools You'll Need

  • 28mm filter socket (the same one you use for the engine-mounted 68157291AA)
  • Ratchet with extension
  • Catch pan (you'll lose about a half-pint of diesel)
  • Shop towels
  • Safety glasses

Step-by-Step Replacement

1. Park on level ground and let the engine cool. The fuel system holds residual pressure — let it sit for 30 minutes after driving.

2. Locate the filter on the driver-side frame rail. Place your catch pan underneath.

3. Open the drain valve at the bottom of the filter. Drain the trapped water and fuel completely.

4. Disconnect the water-in-fuel sensor connector. Just squeeze the tab and pull straight out.

5. Use the 28mm socket to unthread the filter housing. Counterclockwise. It will be tight the first time — the factory torque is real.

6. Lower the old filter and unscrew the water-in-fuel sensor from the bottom of the old housing. Transfer it to the new 68436631AA filter (handle it carefully — the sensor is reusable).

7. Lubricate the new O-ring with clean diesel fuel. Never use motor oil or grease.

8. Hand-thread the new filter until it makes contact, then tighten 3/4 turn with the socket. Do not overtighten — you'll crush the O-ring.

9. Reconnect the water-in-fuel sensor and close the drain valve.

10. Prime the system. Cycle the ignition key to ON (without starting) for 30 seconds, then OFF, then repeat 2-3 times. This lets the lift pump fill the new filter.

11. Start the engine. It may run rough for 20-30 seconds as air clears. Check for leaks at the housing and sensor.

Total time: 30-45 minutes for a first-timer.

Don't Forget the Engine-Mounted Filter

The 68436631AA is only half the fuel system on 2019+ trucks. The engine-mounted mopar 68157291AA fuel filter is the second-stage NanoNet filter that protects the injectors directly. Both filters should be changed together at every service interval — every 15,000 miles or annually, whichever comes first.

Buying them separately wastes money and shipping time. The smart move is the Mopar Fuel Filter Kit 68157291AA + 68436631AA for 2019-2024 RAM 2500-5500 6.7L Cummins — both genuine OEM filters in one kit at $54.99.

Add the Oil Filter — Same Job, Same Day

If you're already under the truck, swap the oil filter while you're there. The Mopar Fuel & Oil Filter Kit 68157291AA + 68436631AA + 5083285AA for 2019-2024 RAM bundles all three filters for $62.99 — that's full annual maintenance done in one trip under the truck.

For background on why the oil filter matters as much as the fuel filters, see our breakdown of why the 5083285AA is the most counterfeited Cummins oil filter.

Common Mistakes to Avoid

  • Overtightening the housing — crushes the O-ring and causes leaks. 3/4 turn past contact is enough.
  • Skipping the prime cycle — running the starter dry can damage the lift pump.
  • Reusing the old O-ring — they take a permanent set after one use. New O-rings come with the OEM filter.
  • Buying aftermarket "compatible" filters — the 68436631AA's water separation rating is critical for protecting the CP4.2 pump. There's no safe shortcut here.
  • Ignoring the water-in-fuel light afterward — if the sensor wasn't seated correctly during transfer, the light will stay on.

When to Replace

RAM specifies 15,000 miles or 12 months for the 68436631AA. In real-world conditions:

  • Light driving (highway, clean fuel stations): 15,000 miles is fine
  • Heavy towing or off-road work: 10,000 miles is safer
  • If the water-in-fuel light comes on: drain immediately, replace soon
  • If you see any of the symptoms described in our bad fuel filter symptoms guide, replace now, not later

Final Word

The mopar 68436631AA isn't optional and it isn't interchangeable. It's the first line of defense for the most expensive component in your truck — the CP4.2 pump. Genuine american mopar filters, installed on schedule, are the cheapest insurance policy your Cummins will ever get. Skip the dodge ram oil change coupons at the dealer and do it yourself in under an hour with the right OEM parts.

Back to blog