Name: 19-24 Ram 6.7L Cummins Fleetguard Rear Chassis Mounted Fuel Filter
Brand: Fleetguard
Price: 48.85 USD
Availability: LimitedAvailability

19-24 Ram 6.7L Cummins Fleetguard Rear Chassis Mounted Fuel Filter

Fleetguard FS20378 Rear Fuel Filter 2019-2024 6.7L Cummins & EcoDiesel

$48.85

Part Number: FS20378
Est. Ship Time: Usually Ships By Next Business Day

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Fleetguard FS20378 Rear Fuel Water Separator - 2019-2024 Ram 6.7L Cummins & EcoDiesel

The Fleetguard FS20378 fuel water separator is the rear (chassis-mounted / under-bed) fuel filter used on 2019-2024 Ram 6.7L Cummins and 3.0L EcoDiesel platforms. This high-efficiency cartridge is responsible for removing water and fine particulates before fuel reaches the primary (under-hood) filter and high-pressure system, making it a critical first line of defense for injector and fuel pump protection.

Modern diesel fuel systems rely on multi-stage filtration, and the FS20378 plays a key role in that process. Positioned at the rear of the truck along the frame rail, this filter removes contaminants early in the fuel flow path. By separating water and filtering down to approximately 2 micron efficiency, it helps reduce the risk of corrosion, injector damage, and high-pressure pump wear.

Why the FS20378 is critical to your fuel system

Rear-mounted water separator - removes water before it reaches sensitive components
Approx. 2 micron filtration for high-pressure common rail protection
Works as the first stage of filtration in the fuel system
Protects injectors and fuel pumps from contamination and wear
Direct replacement for Mopar 68436631AA

Fitment and dual-filter system explanation

The FS20378 is used on:

2019-2024 Ram 2500 / 3500 / 4500 / 5500 - 6.7L Cummins
2020-2023 Ram 1500 - 3.0L EcoDiesel
2020-2023 Jeep Wrangler JL & Gladiator JT - 3.0L EcoDiesel

These trucks use a two-filter fuel system:

Rear filter (this product - FS20378) - primary water separation and pre-filtration
Front filter - Fleetguard FS53000 under-hood fuel filter for final filtration before the high-pressure system

Both filters must be serviced together to maintain proper system protection.

2013-2018 vs 2019-2024 system differences

While 2013-2018 trucks also used a rear-mounted filter, the design differs. Earlier trucks use:

FS20089 frame-mounted filter (2013-2018)

The FS20378 is specific to 2019+ updated fuel systems and is not interchangeable with earlier designs.

Cross reference

Fleetguard: FS20378
Mopar: 68436631AA

Troubleshooting and maintenance insights

Because the FS20378 is the first filtration stage, issues here can affect the entire fuel system. Common symptoms of a restricted or contaminated filter include:

Hard starting or extended crank time
Reduced power under load
Inconsistent throttle response
Premature wear of injectors or fuel pump components

Routine replacement is critical, especially for trucks operating in dusty environments, heavy towing conditions, or areas with variable fuel quality.

Complete filtration system and upgrade options

Front fuel filter: FS53000 under-hood filter
Fuel and oil service bundle: aFe Pro Guard filter kit
Older system comparison: FS20089 (2013-2018)

Upgrade your fuel filtration system

Looking for better protection than stock?

The factory dual-filter system does a good job, but with modern CP4 fuel systems, many owners choose to add additional filtration to reduce contamination risk and extend fuel system life.

2019-2024 Cummins Fleetguard Fuel Filter Upgrade Kit - adds high-efficiency NanoNet filtration at the rear of the truck
Reduces contaminant load before fuel reaches the high-pressure system
Helps improve long-term injector and CP4 pump durability
Simplifies service and can reduce long-term maintenance cost

This upgrade is especially popular for trucks used in towing, daily driving, or areas with inconsistent fuel quality.

Tap a question below to expand

What does the FS20378 filter do?

It removes water and fine contaminants from diesel fuel before it reaches the primary fuel filter and high-pressure system.

Do I need to replace both fuel filters?

Yes - 2019+ trucks use a dual-filter system, and both the rear (FS20378) and front (FS53000) filters should be serviced together.

Is this the same as the 2013-2018 filter?

No - 2013-2018 trucks use a different rear filter (FS20089). The FS20378 is specific to 2019+ systems.

When should I replace this filter?

Replace it at regular service intervals or sooner if contamination, drivability issues, or poor fuel quality are suspected.