How Many Fuel Filters Does a 6.7 Cummins Have? Two — Here Is Where They Are

# How Many Fuel Filters Does a 6.7 Cummins Have? Two — Here Is Where They Are Two. Not one, and they are not the same filter. That trips up more owners than almost any other maintenance question on these trucks, because the two filters carry different filtration ratings, both have to be serviced together, and where the second one lives changed between model years. Everything below comes from Ram's own owner documentation for the 2500/3500 Heavy Duty trucks that carry the Cummins 6.7L, plus Cummins' own engine documentation. Where a figure belongs to a specific model year, that is stated — a service interval from one year's schedule is not a fact about every year. ## The answer: two The manual states the count without hedging. There are two fuel filter assemblies. Both are real service items. Both have their own water drain valve, and both are addressed by the same maintenance line, which matters more than it sounds — replacing one and leaving the other is the most common version of this job done wrong. ## Where each one sits This is where model year matters more than anywhere else on the page, and it is why you will find owners describing a filter you cannot locate. On a 2026 Ram 2500/3500 both filters are on the engine, beside each other. There are two engine mounted fuel filter assemblies mounted side-by-side on the driver side of the engine.oem-30 Because both sit in the same place, both drain valves do too. The best access to the water drain valves is from under the hood.oem-30 The 2024 truck is laid out differently, and this is the layout most Cummins filter advice on the internet is describing. One is located on the driver's side of the engine.oem-31 That first one is reached the same way as on a 2026. The best access to this water drain valve is from under the hood. The second one isoem-31 not on the engine at all. The second one is on the under body, located in front of the rear axle above the drive shaft.oem-31 And it is reached from a different position entirely. The best access to this water drain valve is from under the vehicle.oem-31 So establish which layout your truck has before you start looking. On a 2026 both filters and both drain valves are under the hood together; on a 2024 one of them is beneath the truck, ahead of the rear axle, and you will need a lift or ramps to reach it. ## They are not the same filter This is the detail that turns a cheap job into an expensive one. The two positions are specified to different filtration ratings. Ram's guidance names the parts first — We recommend using Mopar® Fuel Filters. — and then gives the specification for each position. The forward filter is the tighter of the two: Must meet 3 micron rating (front mounted filter).oem-29, oem-30 The rear position is specified differently: Must meet 5 micron rating (rear engine mounted filter).oem-29, oem-30 Three micron in one position, five in the other. Fit them the wrong way round, or fit a filter that meets neither, and you are not saving money — you are changing the filtration the fuel system was designed around. The manual is direct about the consequence: Using a fuel filter that does not meet the manufacturer’s filtration and water separating requirements can severely impact fuel system life and reliability.oem-29, oem-30, oem-31 Read that sentence twice, because it names two requirements rather than one. Filtration is the job everyone assumes. Water separating is the second one, and on a diesel it is the job that decides whether the high-pressure side of the fuel system has a long life or a short one. ## The other job: water separation Ram's own documentation does not call these parts fuel filters when it describes draining them. It calls them the fuel/water separator filters, which is a better name for what they are. Water is the contaminant a diesel injection system cannot tolerate, and the assemblies are built to collect it rather than pass it. The sensor that detects it is a service part in its own right: Water In Fuel (WIF) sensor is reusable. That is worth knowing before you order parts. The sensor comes back out of the old housing and goes into the new one, and the kit is specified to suit: Service kit comes with new o-ring for filter canister and WIF sensor.oem-31 ## The truck will not run without them Neither position is optional, and the engine enforces that on its own rather than leaving it to the owner. On the 2024 truck the engine-mounted housing carries a named feature for it: The engine mounted filter housing is equipped with a No-Filter-No-Run (NFNR) feature.oem-31 The under-body position behaves the same way. The underbody mounted filter housing will cause the engine not to run if no filter is installed.oem-31 So a truck that will not start after a filter change is not necessarily a fuel-system fault. An empty housing, or a cartridge that has not seated, produces exactly that symptom by design. ## Cold weather One more piece of the assembly explains a question owners usually ask separately, which is why these trucks start in real winter. A 12 Volt heater built into the fuel filter housings aid in preventing fuel gelling.oem-30, oem-31 Gelling is diesel's cold-weather failure mode, and heated housings are a designed defence against it rather than an accessory somebody added later. If you run one of these trucks through a northern winter, that heater is part of why it starts. ## When to change them Both filters come out on the same schedule, and the schedule treats them as one job rather than two. Cummins publishes the interval directly on its own engine documentation: Maintenance intervals for fuel filter replacement remains at 15,000 miles (24,000 km).oem-04 Ram's 2026 maintenance plan puts the same job in the same group as the oil change, at Every 15,000 Miles (24,000 Km). The word in the schedule line is **both** — there is no version of this service where you do one filter and leave the other. The oil change that shares that interval has its own ceiling, and it is worth reading because it is written as an absolute rather than a recommendation: Under no circumstances should oil change intervals exceed 15,000 miles (24,000 km) or 12 months or 500 Hours, whichever comes first.oem-01, oem-29, oem-30 ## Where the filters sit in the whole schedule Owners who only ever look up the filter interval miss that it is one line in a maintenance plan built around this engine. The 2026 diesel plan is worth reading as a whole, because several of its intervals are shorter than people assume. It opens earlier than most owners expect, with a fluid check at Every 7,500 Miles (12,000 Km). The cabin air filter comes next, at Every 12,000 Miles (19,000 Km), and then the 15,000-mile group with the oil and both fuel filters. After that the plan spreads out. Brake linings, the drive belt and the axle surfaces are inspected at Every 22,500 Miles (36,000 Km). Wheel bearings are inspected at Every 30,000 Miles (48,000 Km). The transmission fluid change falls at Every 60,000 Miles (96,000 Km). The crankcase ventilation filter is replaced at Every 75,000 Miles (120,000 Km). Power steering fluid is flushed and replaced at Every 97,500 Miles (156,000 Km). The engine air cleaner carries an absolute ceiling of its own, in the same form as the oil interval: Under no circumstances should the engine air cleaner filter exceed 15,000 miles (24,000 km) or 24 months, whichever comes first.oem-29, oem-30, oem-31 There is also a reminder built into the cluster for the emissions-related service, and it is not the oil light. Your vehicle will require emissions maintenance at a set interval.oem-29, oem-30, oem-31 What that reminder covers is named: Emissions maintenance may include replacing the Closed Crankcase Ventilation (CCV) filter element.oem-29, oem-30, oem-31 So a "Perform Service" message on the cluster is a different instruction from an oil change message. One is asking for the emissions-related maintenance line; the other is asking for oil. ## Draining the water out The drain is a separate job from the filter change, it is time-bound, and the manual is specific about when not to do it. First the prohibition: Do not drain the fuel/water separator filter when the engine is running.oem-30, oem-31 Then the trigger. Drain the fuel/water separator filters when the Water In Fuel Indicator Light is ON.oem-30, oem-31 Then the clock, which is the part people miss if they shut the truck off and come back to it later. On a 2026, within 10 minutes of vehicle shutdown, turn the engine mounted filter drain valves (located on the side of the filter assembly) counterclockwise 1/4 turn.oem-30, oem-31 The 2024 truck needs two different amounts of turn, one for each position, which is why knowing your layout matters here too: turn the engine mounted filter drain valve (located on the side of the filter assembly) counterclockwise 1/4 turn, and turn the under body mounted filter drain valve (located on the bottom of the filter assembly) counterclockwise 1 full turn.oem-31, oem-30 A quarter turn on the engine, a full turn underneath. Then the ignition goes to ON and the water is allowed to run out until what comes out is fuel rather than water. Closing the drain has a specification too, and over-tightening it is a genuinely expensive mistake. On the 2026 assemblies, rotate the 1/4 turn drain valves fully clockwise to their stops.oem-30 Then continue turning the drain 1/2 of a turn to properly compress the seal.oem-30, oem-31 Stop there. Over-compression of the seal due to over- tightening of the drain will damage the seal, cause a leak, and require the entire sensor to be replaced.oem-30, oem-31 That is the whole reason the manual bothers to specify a fraction of a turn on a drain valve: the seal it compresses is part of the sensor assembly, and crushing it turns a five-minute drain into a parts order. ## The light that tells you which problem you have There is one dash light on this system that is not an advisory, and the number of chimes attached to it turns it from a single warning into a usable diagnostic. The Water In Fuel Indicator Light will illuminate when there is water detected in the fuel filters.oem-30, oem-31 When the system finds water while the engine is running, the light arrives with a count: an audible chime will be heard five times.oem-30, oem-31 One chime is a different message entirely: If the Water In Fuel Indicator Light comes on and a single chime is heard while you are driving, or with the ignition switch in the ON position, there may be a problem with your water separator wiring or sensor.oem-30, oem-31 So count the chimes before deciding what you are dealing with. Five means the separator has caught water and the filters want draining. One means the truck is reporting a fault in the circuit that detects water, and no amount of draining will change it. If the light is on before you start, the instruction is unambiguous: If the Water In Fuel Indicator Light remains on, DO NOT START the engine before you drain water from the fuel filters to avoid engine damage.oem-30, oem-31 The light also does not go out the instant the water does, which catches people out into thinking the drain failed. Upon proper draining of the water from both fuel filters, the Water In Fuel Indicator Light will remain illuminated for approximately 10 seconds.oem-30, oem-31 And if the drain was done the way the manual tells you not to do it, the delay is far longer. If the water was drained while the engine was running, the Water In Fuel Indicator Light may remain on for approximately three minutes.oem-30, oem-31 ## Fitting the new ones Two details in the procedure run against habits picked up on other engines, and both are stated as cautions rather than suggestions. The first is priming. Do not prefill the fuel filter when installing a new fuel filter.oem-30, oem-31 That is the opposite of what most people do, and the manual gives the reason: It is best to install the filter dry and allow the in-tank lift pump to prime the fuel system.oem-30, oem-31 The second is the lid. Install lid onto housing and tighten to 22.5 ft-lb,oem-30, oem-31 which is a specification rather than a feel. The o-ring is a fitted part too, not a dry one: Install new o-ring back into ring groove on the filter housing and lubricate with clean engine oil.oem-30, oem-31 Once it is back together, a rough-running engine is expected rather than alarming. The engine may run rough until the air is forced from all the fuel lines.oem-30, oem-31 There is a limit on how hard you may chase it, though, and it protects the starter rather than the engine: Do not engage the starter motor for more than 15 seconds at a time.oem-30, oem-31 ## The short version Two filters. On a 2026 Ram 2500/3500 both are on the engine, side by side on the driver side, and both drain valves are reached from under the hood. On a 2024 Ram 2500 one is on the driver's side of the engineoem-31 and the second is under the body ahead of the rear axle, reached from underneath. Three micron in the front position, five micron in the rear, and they are not interchangeable. Both replaced together at 15,000 miles. The new filter goes in dry, the lid gets torqued, and the drain valve gets closed to a specification rather than to feel. And if the water-in-fuel light comes on, count the chimes before you reach for a tool — then drain the water before you drive. ## Sources 1. 2024 Ram 2500 Owner's Manual — Mopar vehicle information (Stellantis North America) 2. 2026 Ram 2500/3500 Owner's Manual — Mopar vehicle information (Stellantis North America) 3. 2026 Ram 2500/3500 Owner's Handbook, maintenance schedule — Mopar vehicle information (Stellantis North America) 4. Cummins Inc., 6.7L Cummins engine information, 2019 Chassis Cab