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5 Diesel Fuel Filter Replacement Tips

Burgundy pickup truck on dirt road in front of green pasture

Your diesel-powered vehicle is most likely equipped with a fuel filter — a part that must be changed out regularly per your owners manual. Diesel fuel filter replacement ensures that water and debris doesn’t pass through to contaminate and potentially damage a vehicle’s injection system.

Diesel Fuel Filter Replacement Tips

Always reference your owners manual for change intervals for all parts, including diesel fuel filters. Most vehicles have one filter, but some newer trucks have two: primary and secondary filters. Typically, both are sold together, which ensures you have the right replacement parts based on your vehicle’s make, model and model year. Here’s how to replace your diesel fuel filter.

Step 1: Assemble the tools. You’ll need a few tools to complete the job, beginning with gloves and an eye shield for yourself. A catch bucket, such as an oil pan, is ideal to hold the drained fuel, which you can take to your local recycling center or back to the store where you purchased it (if they accept the material). You’ll also need a nut driver or flat-head screwdriver as outlined in the manual’s replacement instructions.

own photoStep 2: Locate the filter(s). Fuel filters are usually accessible from either the engine’s top side or underneath. In some engine compartments, removing the fender well liner makes this job easier. The well is held in place by snap fasteners, so they’re easy to remove. If your diesel engine also contains an integrated water-in-fuel sensor, it must be removed from the old filter and installed in the new one. Be sure to check with the manufacturer or a repair manual on how to do so.

Step 3: Remove and replace the filter. Use a wrench or socket to loosen the filter’s cap. Next, detach the filter from the cap or lift it from its housing. Find the “O” ring on the cap, and separate it from the housing with a flat-head screwdriver. You won’t need to keep the old ring as your replacement filter comes with a new one. Lubricate the housing and slip the new “O” ring in place. Then, insert the new filter into the cap, and place it in the housing. Hand-tighten the filter, then follow with a torque wrench to secure. Don’t forget to replace the drain plug.

Step 4: Locate the second filter. Typically, a secondary filter is located on top of the engine, which means the primary one is found on the driver frame rail, midway along the chassis. Remove and replace the filter, but leave the fuel in place. Repeat the process outlined with the primary filter.

Step 5: Prime the fuel system. Before you drive your vehicle, you’ll want to prime the system. This typically involves cycling the system multiple times to purge it of air and draw in fuel. Reference your owners manual for vehicle-specific directions.

Changing your diesel fuel filter per the manufacturer’s interval recommendations will help keep your vehicle running optimally. If you don’t change your filter, engine performance will degrade, which could lead to pricey fuel system repairs.

Check out all the fuel filters available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on diesel fuel filter replacement, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photos courtesy of Matt Keegan.


Matthew C. Keegan View All

Matt Keegan has maintained his love for cars ever since his father taught him kicking tires can be one way to uncover a problem with a vehicle’s suspension system. He since moved on to learn a few things about coefficient of drag, G-forces, toe-heel shifting, and how to work the crazy infotainment system in some random weekly driver. Matt is a member of the Washington Automotive Press Association and is a contributor to various print and online media sources.

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