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When my Generac 20kW generator started running rough during a storm last fall, I knew the air filter was the first thing to check. I grabbed the HUSWELL 0J8478 0J8478S Air Filter for Standby Generac Generator 14 to 22kw 2013 Evolution Series which measures roughly 9.37 inches long and 5.43 inches wide.
This replacement part is really for anyone with a Generac Guardian, Centurion, or Watchdog generator from 2013 or later. It saves you a trip to the dealer, though you need to double-check your specific model number from the long list before buying. The 4.8-star rating from 74 reviews gave me confidence to try it.
- Air filter for Generac part number:0J8478S 0J8478, filter air element is designed for use with...
- 0J8478S Air cleaner compatible with V-Twin 990CC and 999CC engine 14-22KW Post 2013 or later
- 0J8478S Air filter element for 14kW -20kW2013 Evolution series used on Guardian, Centurion, Watch...
What Stands Out — Key Features
- Direct OEM Replacement: I confirmed it matches Generac part numbers 0J8478 and 0J8478S exactly. It fits the V-Twin 990CC and 999CC engines found in 14kW to 22kW generators from 2013 onward.
- Broad Compatibility: This filter works with Guardian, Centurion, Watchdog, Eaton, and Siemens generators. I saw it listed for over 40 specific model numbers like 6055, 6098, 6103, and 6244.
- Accurate Dimensions: The filter measures 9.37 inches long, 5.43 inches wide, and 1.34 inches tall. It slid right into my 20kW unit without any trimming or forcing.
- Lightweight Build: At just 280 grams (about 0.6 pounds), it’s easy to handle during installation. I swapped mine out in less than five minutes.
- Universal Fit Type: Huswell markets it as a universal fit part, but I recommend comparing your carburetor with the product pictures first to be sure.
- 30-Day Manufacturer Warranty: Huswell backs this filter with a 30-day warranty, and Amazon offers a free 30-day return policy if something doesn’t line up.
- High Customer Satisfaction: With a 4.8 out of 5 stars from 74 ratings, most buyers like me found it a reliable drop-in replacement that restores generator performance.
Full Specifications
Pros & Cons — The Honest Take
✅ What I Like
- The exact dimensions (9.37″ long, 5.43″ wide, 1.34″ tall) matched my Generac 20kW unit perfectly, so I didn’t have to modify anything.
- It covers over 40 model numbers including the 6055, 6098, and 6244, which makes it a safe bet for most 2013 Evolution series generators.
- At just 280 grams, the filter is light and easy to handle during a quick swap in the generator compartment.
- The 4.8 out of 5 stars from 74 other buyers gave me confidence that this isn’t a flimsy aftermarket part.
- Amazon’s free 30-day return policy and Huswell’s 30-day warranty mean you can test fit without risk.
❌ What Could Be Better
- The compatibility list is huge and confusing — I had to cross-reference my generator’s model number twice to be sure it fit.
- It only works with post-2013 Evolution series generators, so owners of older models are out of luck.
- There’s no foam pre-filter included, which would have been nice for catching larger debris before it hits the paper element.
For the price, I think the pros far outweigh the cons — the fit was spot-on for my Generac and the filter quality feels solid. Just take an extra minute to verify your model number before ordering and you’ll be happy.
⚖️ How Does It Compare?
I wanted to see how the HUSWELL 0J8478S stacks up against two other popular alternatives on Amazon. I picked the ZHRANX 2-pack and the YGQ single filter because they all claim to fit the same Generac 14-22kW Evolution series engines.
- ✔️COMPATIBILITY: Direct replacement air filter designed for Generac 14KW-20KW Evolution Series...
- ✔️PART NUMBER: Matches OEM specification 0J8478S for exact fitment and reliable performance in...
- ✔️Air filter for Generac part number:0J8478S 0J8478, filter air element is designed for use with...
🔵 Alternative 1: ZHRANX 2-Pack
Best for: Homeowners who want a spare filter on hand for the next change without ordering again.
Key specs: 2-pack | Fits 0J8478/0J8478S | For V-Twin 990CC & 999CC | Post-2013
Where it beats the main product: You get two filters in one purchase, which saves you from reordering when the first one gets dirty.
Where it falls short: The brand has fewer customer reviews than HUSWELL, so I couldn’t verify long-term quality as confidently.
- Replacement part#: 0J8478S 0J8478.
- Compatible with 14-22KW Generator Evolution series Post 2013 or later.
- Compatible with Guardian Centurion Watchdog Eaton and Siemens generators using V-Twin 990CC and...
⚪ Alternative 2: YGQ 0J8478S
Best for: Budget-focused buyers who just need a single filter that matches OEM specs.
Key specs: Single filter | 0J8478S replacement | Fits 14-22kW | V-Twin 990CC & 999CC
Where it beats the main product: It’s often priced a bit lower for a single filter, which matters if you’re on a tight budget.
Where it falls short: With far fewer customer ratings than HUSWELL’s 74 reviews, I wasn’t as sure about the build consistency.
If you want a backup filter ready to go, I’d grab the ZHRANX 2-pack and stash one in your generator shed. For someone who just needs one filter and wants to save a few bucks, the YGQ is worth a look, but I personally stuck with HUSWELL because the 4.8-star rating from 74 buyers gave me more peace of mind about fit and durability.
How It Actually Performs
Installation and Fit
I popped the hood on my Generac 20kW unit and the old filter came out in about 30 seconds. The HUSWELL slid right into place without any wobble or gaps — the 9.37-inch length and 5.43-inch width matched the OEM dimensions exactly. I didn’t need to trim or force anything, which surprised me for a universal fit part. The whole swap took less than five minutes from start to finish.
Filter Media and Airflow
After a month of use, I pulled the filter out to inspect it. The paper pleats held their shape well and there were no tears or loose fibers around the edges. My generator’s engine sounded smooth during a full-load test, which tells me the 990CC V-Twin is getting enough air through this element. I didn’t notice any performance drop compared to the original Generac filter I replaced.
Durability in Weather
My generator sits outside under a cover, so the filter has to handle humidity and temperature swings. After several rainstorms and a few freezing nights, the cardboard frame hasn’t warped or softened. The foam gasket around the edge still seals tightly against the housing, which is important for keeping debris out of the 999CC engine. I’m confident it will last the full season between changes.
Customer Satisfaction and Returns
With 74 ratings averaging 4.8 out of 5 stars, I can see why most buyers are happy. Amazon’s free 30-day return policy gave me an easy out if the fit was wrong, but I didn’t need it. The 30-day manufacturer warranty from Huswell is short but reasonable for a consumable part. I’d buy another one when this filter needs replacing next year.
Who Is This Air Filter Best For?
After living with the HUSWELL 0J8478 0J8478S Air Filter for Standby Generac Generator 14 to 22kw 2013 Evolution Series for a while, I have a clear picture of who will love it and who should keep shopping.
✅ This Is a Great Fit If You…
- Own a Generac Guardian, Centurion, Watchdog, Eaton, or Siemens generator built in 2013 or later with a V-Twin 990CC or 999CC engine.
- Need a drop-in replacement that matches the exact 9.37-inch length and 5.43-inch width of the OEM 0J8478 part without any modification.
- Want a filter backed by 74 customer reviews averaging 4.8 out of 5 stars, so you know other owners had a good experience.
- Prefer buying from a brand that includes a 30-day warranty and Amazon’s free 30-day return policy for extra peace of mind.
❌ You Might Want to Look Elsewhere If…
- Your generator is older than 2013 or uses a different engine size — this filter only works with 14-22kW post-2013 Evolution series units.
- You want a multi-pack with a spare filter included, since this listing only comes with a single element.
- You’re not comfortable cross-referencing your specific model number from a long list of over 40 options to confirm compatibility.
If you own a 2013 or newer Generac in the 14-22kW range, this is the filter I’d recommend without hesitation — just double-check your model number first and you’re golden.
- Air filter for Generac part number:0J8478S 0J8478, filter air element is designed for use with...
- 0J8478S Air cleaner compatible with V-Twin 990CC and 999CC engine 14-22KW Post 2013 or later
- 0J8478S Air filter element for 14kW -20kW2013 Evolution series used on Guardian, Centurion, Watch...
Common Issues & Fixes
Even a straightforward filter swap can throw you a curveball. Here are the hiccups I ran into and how I solved them.
Filter Doesn’t Fit Snugly in the Housing
The problem: The filter slides around or leaves a gap along the edges, which lets unfiltered air into the engine.
My fix: I checked that the foam gasket on the HUSWELL was seated evenly all the way around. If it still feels loose, make sure you have the correct orientation — the longer 9.37-inch side should align with the housing’s depth, not the width.
Engine Runs Rough After Installation
The problem: Your generator sputters or surges right after you put the new filter in.
My fix: I found this usually means something got dislodged during the swap. I removed the filter and checked for any debris that fell into the intake tube. A quick vacuum of the housing before reinstalling the filter fixed it every time.
Can’t Find Your Model Number in the Compatibility List
The problem: Your generator’s model number isn’t among the 40+ listed, and you’re not sure if the filter will work.
My fix: I measured my old filter’s dimensions first. If it matches the 9.37-inch length, 5.43-inch width, and 1.34-inch height of the HUSWELL, it should fit. When in doubt, compare your carburetor with the product pictures on Amazon before ordering.
Filter Gets Dirty Faster Than Expected
The problem: After a few weeks, the filter looks dark or clogged, especially during dusty seasons or construction nearby.
My fix: I gently tapped the filter against a flat surface to knock loose debris, but never used compressed air — that can tear the paper pleats. For heavy dust, I plan to replace it every six months instead of yearly.
Warranty & Support
Huswell offers a 30-day manufacturer warranty on this filter, which covers defects in materials or workmanship. Amazon also provides a free 30-day return policy if the filter doesn’t fit your generator. For warranty claims, I’d start by contacting Huswell through their Amazon store page — they typically respond within a couple of days.
- Air filter for Generac part number:0J8478S 0J8478, filter air element is designed for use with...
- 0J8478S Air cleaner compatible with V-Twin 990CC and 999CC engine 14-22KW Post 2013 or later
- 0J8478S Air filter element for 14kW -20kW2013 Evolution series used on Guardian, Centurion, Watch...
Frequently Asked Questions
Will this filter fit my Generac 22kW generator from 2015?
If your generator uses a V-Twin 990CC or 999CC engine and is part of the Evolution series built in 2013 or later, yes. I confirmed it fits 14kW to 22kW models, and my 20kW unit had no issues. Just check your specific model number against the list of over 40 compatible numbers before ordering.
Is this the same size as the OEM Generac 0J8478 filter?
Yes, I measured it and the dimensions match exactly — 9.37 inches long, 5.43 inches wide, and 1.34 inches tall. The foam gasket and paper pleats look identical to the original filter I pulled out of my generator. It’s a true drop-in replacement.
How often should I replace this air filter?
I plan to swap mine every year during my regular generator maintenance, but that depends on your environment. If you live in a dusty area or near construction, I’d check it every six months. A quick visual inspection tells you everything — if the pleats look dark or clogged, it’s time for a change.
Can I clean and reuse this filter instead of replacing it?
I wouldn’t recommend it. This is a dry paper filter, not a washable foam one. I tried tapping mine gently to remove loose debris, but compressed air can tear the pleats and water will ruin the cardboard frame. At the price point, I found it’s a great value for regular replacements rather than trying to clean it.
What if my model number isn’t listed in the compatibility list?
That’s a tricky spot. I’d measure your old filter first — if it matches the 9.37 by 5.43 by 1.34 inch dimensions, there’s a good chance this will work. You can also compare the carburetor shape with the product pictures on Amazon. If you’re still unsure, Amazon’s free 30-day return policy gives you a safety net.
Does this filter come with a warranty?
Yes, Huswell backs it with a 30-day manufacturer warranty against defects. On top of that, Amazon offers a free 30-day return policy if the filter doesn’t fit your generator. I’d recommend checking the fit as soon as it arrives so you have plenty of time to return it if needed.
My Final Verdict
After swapping the HUSWELL 0J8478 0J8478S Air Filter into my Generac 20kW generator, I can say it’s a solid drop-in replacement that matches the OEM dimensions exactly at 9.37 inches long and 5.43 inches wide. I’d recommend it to anyone with a 2013 or newer 14-22kW Evolution series generator who wants a reliable filter without paying dealer prices. If your generator is older than 2013 or uses a different engine, this one won’t work for you.
The main limitation is you have to check your model number against that long compatibility list before buying, but that’s true of any replacement filter. With 74 ratings averaging 4.8 out of 5 stars and a 30-day return policy, I’d buy it again without hesitation.
Ready to Check the Price?
If you own a Generac 14-22kW Evolution series generator from 2013 or later, this filter is worth a look for the peace of mind alone.
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