2020-2025 Duramax Air and Cabin Filter Kit Guide (A3248C / CF185)

The Filter I Bought Wrong at 30,000 Miles

I ordered an air filter for my 2021 Silverado 2500 HD, and the listing said “fits 2017-2025 Duramax.” It arrived, and it fit. It dropped into the airbox, the lid closed, and I ran it for 18,000 miles before I learned what I had actually done.

The 2020+ L5P airbox is not the same airbox as the 2017-2019 truck. GM redesigned the intake housing when the L5P got its second revision, and the panel element changed with it — A3244C for 2017-2019, A3248C for 2020 and up. Both are roughly the same rectangle. Both drop in. The difference is the seal profile, and the seal is the entire job.

An air filter that fits but does not seal lets the airbox lid clamp down on a rubber edge that does not match the channel it is supposed to compress into. The lid closes. It looks right. And every mile after that, a small percentage of the air going into your turbocharger goes around the filter instead of through it.

That is not a filter problem. That is an unfiltered dust problem, and on a VGT turbo turning over 100,000 RPM with intake valves and cylinder walls downstream, unfiltered dust is abrasive. Silica grinds. It does not melt, it does not burn, it does not care that the trucks behind you are also out here in the dust. It just keeps cutting.

I got lucky. My oil analysis at the next change came back clean enough. But I paid for a second filter I did not need and I spent 18,000 miles trusting a seal that was never designed for my lid.

That is why this guide exists, and why it covers two filters instead of one.

Why the Air Filter on a 2020+ Duramax Matters More Than You Think

Gas engines tolerate a marginal air filter. A naturally aspirated V8 pulling filtered-feeling air just loses a little top-end. On an L5P, the air path is doing different work.

The turbo multiplies everything. The variable-geometry turbocharger on the 6.6L Duramax compresses intake air to build boost, and the compressor wheel spins faster than most people can picture — well past six figures in RPM. An abrasive particle that gets past the filter does not get one chance to damage one cylinder wall. It gets one chance to hit the compressor wheel at full rotational speed, and if it damages the wheel, the imbalance gets worse with every revolution. Turbocharger replacement on these trucks is not a small invoice.

The airbox is not a restriction at stock power. This is the part the aftermarket does not want you to hear. GM’s powertrain engineers sized the factory intake to feed 445 horsepower in the L5P. A clean paper element in good condition does not choke that. A dirty one does, and a leaking one is worse than a dirty one because the leaking one sends dust through while the media still looks reasonably clean when you pull it.

The symptoms arrive late and quietly. You will not feel a properly-sealed filter working. You will feel a clogged one: throttle response softens, fuel economy drops a point or two, exhaust gas temperature climbs under load because the engine is working harder for the same air, and on an emissions-equipped truck the DPF starts asking for regens more often because higher EGT drives more soot loading. A severe restriction can set an underboost code. By the time any of that is obvious, you have been driving on a compromised intake for thousands of miles.

The cabin filter is doing a job nobody assigned it. The CF185 sits behind the passenger-side glovebox and filters every cubic foot of air the HVAC system pulls into the cab. On a diesel truck, the fresh-air intake draws from the base of the windshield — directly above the engine bay, which holds the turbo, the crankcase ventilation, and the exhaust. Whatever that region produces passes through the cabin filter before it reaches your face. Particulate media catches the dust. Only the electrostatic layer catches the sub-micron soot and the odor-causing compounds that make a cab smell like the truck stop you idled at last week.

What You Actually Get

The TruckTok 2020-2025 6.6L Duramax Air & Cabin Filter kit is a two-filter set. SKU FI-G-25-03/25-04, priced at $51.28.

A3248C engine air filter. A prism-shaped panel element that seats in the passenger-side airbox of the 2020+ L5P. It has three bottom locating slots and a top notch, so it only goes in one way — if it does not drop cleanly, it is upside down. The perimeter uses a flexible silicone seal that compresses against the airbox channel when the lid closes, which is what makes a correctly-specified filter airtight instead of merely present.

OEM cross-reference: A3248C, 84435887, CA12368, WA10935. Baldwin lists PA10426 as an equivalent, Wix lists WA10935, Pronto lists PA99537.

CF185 cabin air filter. An electrostatic element with an activated-carbon layer, sized for the 2500/3500 HD HVAC box. The electrostatic media holds a permanent charge that attracts particles too small for physical capture — diesel soot nanoparticles, brake dust, PM2.5 highway haze — and the carbon layer adsorbs the gaseous compounds that carry odor. A plain particulate filter catches visible dust and pollen. It cannot touch the smell.

OEM cross-reference: CF185, 13508023, WP10327, PC99231, C31382, CC1382, 13356916. GM sells this same part number for well over a dozen unrelated vehicles — Malibu, Cruze, Equinox, Acadia, LaCrosse, CTS — which tells you the HVAC box geometry is shared across the GM portfolio, not that the filter is generic. Buy by part number, not by picture.

Replacement intervals, from the product spec and the factory schedule:

The engine filter is a mileage item. The cabin filter is a calendar item as much as a mileage one — the media loads with organic matter (pollen, insect fragments, leaf debris) that supports microbial growth, and that growth is what produces the smell. Waiting for the smell means waiting until the filter has been saturated for months.

What You Actually Pay: OEM, eBay, Amazon and Doc’s

Prices verified October 2026. This is the comparison that matters, because the two filters in this kit have very different price behavior across channels.

Read it honestly. This kit is not the cheapest way to buy two filters, and anyone claiming otherwise is not looking at the same shelf.

• Against Doc’s Diesel, the math is close: their air filter plus their cabin filter lands at $49.98, about $1.30 under this kit. That is not a meaningful gap, and their air filter is a third-party element without the OE seal profile. If you are already ordering from Doc’s and want one shipment, that is a real choice.
• Against the GM dealer counter, this kit is roughly 40% cheaper for the same two part numbers in one box instead of two counter visits.
• Against eBay’s genuine-ACDelco listings, the comparison is not close — $88.26 for the air filter alone versus $51.28 for both filters here.
• Against the $27 white-label two-pack, remember what the white-label removes. The air filter’s whole value is the seal that keeps unfiltered air out, and a listing that does not publish a seal spec is asking you to find out on your own turbo. The cabin filter’s whole value above a plain particulate filter is the electrostatic and carbon layer, and a listing that says “cabin air filter” without “activated carbon” is selling you the layer that does not remove odor.

The honest framing: buy this kit if you want both filters, correct part numbers, and one order. Buy Doc’s if you already have an account and do not mind two shipments. Buy the cheapest listing you can find only if you are comfortable that the thing you are optimizing is price and not filtration.

The dealer upsell, in real numbers. A dealer service visit is a good place to see what the same air filter costs when someone else installs it. One owner who documented the conversation was quoted $55 for the part — “what we pay for the part” — plus $15 of labor, $70 total, to change a single air filter he could buy for about $15. Nobody quoted him the price until he asked. That is the pattern worth remembering: the service advisor holds up a dirty element, says “this should be replaced,” and does not volunteer a number. Ask for the number every time, then decide — because on this kit, $70 is more than both filters, delivered.

What to Look For When Buying

1. Match Airbox Generation (A3248C vs A3244C). Verify engine generation. The 2020–2025 L5P uses A3248C. The 2017–2019 L5P uses A3244C. While physically similar, the perimeter sealing profile differs — using an A3244C in a 2020+ box creates an unsealed gap.

2. Silicone Perimeter Sealing Spec. Demand an OEM-spec molded flexible silicone perimeter. Cheap cut-foam gaskets deform under engine heat, creating an unfiltered dust bypass path into the turbo compressor wheel.

3. Electrostatic & Activated Carbon Layer for Cabin Filter. Ensure the cabin filter explicitly features both an electrostatic media layer and a dark activated carbon layer (CF185 / 13508023). Plain paper cabin filters stop dust but fail to adsorb raw diesel exhaust odors and sub-micron PM2.5 soot.

4. Part Number Cross-Reference Verification. Verify explicit part numbers: Air filter A3248C / 84435887 / 84262965 and Cabin filter CF185 / 13508023 / 13508024 / 13356916.

5. Service Interval Alignment. Replace cabin air filters every 12,000–15,000 miles / annually and engine air filters every 30,000 miles (shortened to 15,000 miles in severe/dusty service).

Installation Guide: Step-by-Step Order

Step 1: Replace Engine Air Filter (A3248C)

1. Open the hood and locate the airbox on the passenger side.
2. Release the airbox lid fasteners and lift the lid clear.
3. Vacuum & Clean Housing: Remove dirty filter and vacuum out accumulated leaves and grit sitting in the airbox base.
4. Locating Slots Alignment: Seat new A3248C filter into the housing, ensuring the 3 bottom locating slots and top notch align perfectly so the silicone perimeter seal sits flat in its channel. Fasten lid.

Step 2: Access Cabin Air Filter Slot

1. Empty lower glovebox contents.
2. Slide the right-side damper cord clip down to unhook it, allowing it to retract gently.
3. Squeeze both upper side stops inward while lowering glovebox to release it from the dash.

Step 3: Replace Cabin Air Filter (CF185)

1. Locate the rectangular access door behind the glovebox.
2. Pinch side clips, remove door, and slide out dirty filter. Vacuum loose debris from housing cavity above blower wheel.
3. Slide fresh CF185 carbon filter in with AIR FLOW arrow pointing DOWN toward the blower.
4. Snap door back on until you hear two distinct clicks.

Step 4: Reassemble Glovebox & Verify Airflow

1. Re-hook lower glovebox hinges, squeeze side stops past dash, and snap damper cord back into keyhole slot.
2. Turn ignition ON, set HVAC blower to MAX, and verify strong, odorless airflow across all vents.

Five Expensive Mistakes

Mistake #1: Buying the 2017-2019 air filter for a 2020+ truck

A3244C and A3248C are the same shape and roughly the same size, and marketplace listings routinely claim one filter fits both. It does not seal. An unsealed air filter is not a slightly worse filter — it is a dust injection port aimed at a turbocharger that spins past 100,000 RPM. This is the most expensive mistake on this list because the damage is gradual, invisible, and irreversible.

Mistake #2: Reading “cabin air filter” and assuming it removes diesel smell

A plain particulate cabin filter catches dust and pollen by size exclusion. Diesel odor is carried by gaseous compounds and sub-micron soot, and neither of those is stopped by a paper element. Only the activated-carbon and electrostatic layers address that. If the listing you bought does not say “carbon” or “charcoal,” you bought a filter that will do nothing about the smell, no matter how often you change it.

Mistake #3: Letting the engine air filter go by calendar instead of inspection

The factory interval is 30,000 miles, with an inspection at 15,000. In dust, gravel, agricultural work or construction, those numbers are optimistic. If you tow on unpaved access roads or work near a jobsite, 15,000-20,000 is the realistic interval. Check the element at every oil change — it takes two minutes and it is the difference between replacing a $32 filter and replacing a turbocharger.

Mistake #4: Cleaning the engine air filter with compressed air

Compressed air removes loose surface dust and, in the process, tears and stretches the micro-pleats. A pleated element depends on the geometry of those pleats for its surface area and its dust-holding capacity, and once they are distorted, the filter is simultaneously more restrictive and less effective. A light tap of the frame on a hard surface to dislodge loose debris is fine. Blowing it out with a compressor is not a service — it is a way to convert a working filter into a worse one.

Mistake #5: Waiting for a smell before changing the cabin filter

By the time a cabin filter smells, it has been saturated for months. The odor is the visible end of a process that started with microbial growth on the trapped organic matter — pollen, insect fragments, leaf debris — that a fresh filter does not carry. Change it annually or on mileage, and if you want a quick sanity check, pull it out and hold it up: a filter that has done its job looks gray-brown and heavy, and one that has done nothing useful looks like a new one with a light dusting.

Frequently Asked Questions

Will these filters trigger a check engine light or upset the MAF sensor?

No. Both are molded to factory dimensions and maintain normal intake airflow and pressure readings. A mass airflow sensor concern comes from oiled aftermarket filters that shed oil onto the sensor element, not from a properly sealed dry paper element.

Can I blow out the engine air filter with compressed air to make it last longer?

No. Compressed air tears and expands the micro-pleats, which reduces both filtration accuracy and dust-holding capacity. Gentle tapping to dislodge loose debris is acceptable. Once the media is loaded, replacement is the answer.

Will heavy rain or humidity ruin the engine air filter?

No. The media is a moisture-resistant synthetic blend that resists saturation and does not collapse when wet. Water ingestion into the intake tract is a separate concern about the intake path, not about the filter element failing.

Does the electrostatic charge in the cabin filter wear out over time?

No. The charge is infused into the synthetic fibers during manufacturing and remains active through the filter’s service life. It does not degrade with humidity or age — the filter becomes saturated with captured material long before the charge is a factor.

What is the difference between A3248C and A3244C?

A3244C fits 2017-2019 L5P trucks. A3248C is the element for the 2020+ airbox. The difference is the seal profile that matches the updated lid geometry. An A3244C may physically drop into a 2020+ airbox but will not compress correctly against the channel, which allows unfiltered air to bypass around the edges. Use A3248C for 2020-2025.

Is the CF185 really electrostatic, and does it actually do anything?

Yes. It uses a synthetic media layer with an embedded charge that attracts sub-micron particles — diesel soot, brake dust, PM2.5 — that a paper layer cannot capture by size. A standard particulate filter catches what you can see. An electrostatic filter with a carbon layer also addresses what you can smell.

How often should I change the cabin air filter?

Every 12,000-15,000 miles or annually, whichever comes first. In high-pollen, agricultural, or heavy-traffic environments, check it at 6,000-10,000 miles and shorten the interval. The filter loads on environment, not odometer alone.

My truck only has 20,000 miles. Do I really need the cabin filter already?

Cabin filter wear depends on where you drive, not how far. A truck that sits in traffic and parks outside in a high-pollen area can load its cabin filter in a single season. Pull it and look — that takes less time than reading this answer.

Does the Silverado/Sierra 1500 use the same filters?

No. The HD trucks (2500/3500) use the A3248C and CF185. The 1500 has a different airbox and HVAC box and takes different part numbers. This kit is for the 6.6L Duramax HD trucks only.

What happens if I only replace one of the two filters?

You leave one of the two air paths compromised. Leaving a dirty engine air filter in place raises intake restriction and dust bypass risk; leaving a saturated cabin filter in place leaves you breathing what it should have caught. They run on different clocks — that is exactly why bundling them means you actually change the one you usually forget.

Can I upgrade to oiled performance air filters instead?

You can, and the tradeoff is real. An oiled cotton-gauze filter flows more air but filters less fine dust, and over-oiling contaminates the MAF sensor and can trip codes. For a work truck that spends its life in dust, a dry OEM-spec element replaced on schedule is the safer choice. Under Magnuson-Moss, a dealer has to prove a specific aftermarket part caused a failure to deny warranty coverage — but an engine that fails from dust ingestion after an aftermarket intake leaves an easy paper trail in the oil analysis.

Is the 2024+ Duramax the same filter?

Some catalogs show a superseded engine air filter number for the newest model years, because GM revises sealing materials and part numbers over time. The cabin filter number has carried further. Check your specific model year against the VIN before ordering rather than trusting a marketplace year range — this is one of the few places where the year on your door sticker matters more than the listing title.

Should I let the dealer or a quick-lube shop replace the air filter?

You can, and there is no warranty consequence if you use the correct part number — under Magnuson-Moss a dealer has to prove a specific part caused a failure to deny coverage. But know the math. Shop labor is charged in whole increments, so a two-minute air filter change gets billed as a line item that can exceed the part. One documented dealer visit quoted $55 for the part plus $15 to install — $70 for a filter that retails around $15. If a shop offers to change it, ask for the price before you agree, and if the element is only lightly dusted, there is nothing wrong with declining and doing it yourself at the next interval.

What else should I do while I have the glovebox apart?

Check the cabin filter housing for debris, and confirm the access door latches on both clips. If the blower has started making noise, a filter that slipped past a poorly-seated door is a common cause. This is also a good moment to look at whether the HVAC system is holding airflow — a restricted filter strains the blower motor and reduces the air the evaporator sees, which shows up as weaker A/C in summer.

Get Both Filters, in One Box

If you have been changing your oil on schedule and never once looked behind the glovebox, this kit closes the gap. One order puts the A3248C engine air filter and the CF185 electrostatic cabin filter on your bench at the same time — correct part numbers for the 2020-2025 L5P airbox, one box instead of two counter visits.

Get the 2020-2025 Duramax Air & Cabin Filter Kit

Want to confirm fitment against what other owners are running? A few threads worth reading:

• 2020-2025 Silverado/Sierra 6.6L Duramax Air Filter — Replaces A3248C
• 2020-2026 Silverado/Sierra Cabin Air Filter — Replaces CF185

Legal Disclaimer

This guide is for general informational purposes only and is not a substitute for your vehicle’s factory service manual or the advice of a qualified diesel technician. Always verify the correct part numbers for your specific model year, VIN, and configuration before purchasing or installing filters. Installation of any aftermarket or replacement part is performed at your own risk; the author and retailer assume no liability for damage, injury, or loss arising from the use of this information or the products referenced. Filter change intervals are manufacturer recommendations and should be adjusted for your driving conditions, towing load, and environment.