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If you own a Generac 13kW standby generator and need an air filter that actually fits older models, finding the right replacement can be a headache. I’ve tested seven different 0J8478S-style filters to see which ones seal properly on older air-cooled engines without rattling loose.
Every filter on this list is built to replace the OEM 0J8478S part number, so they’re all designed for Generac’s Evolution Series engines from 2013 and newer. I picked these seven based on three hard criteria: correct fitment on 13kW units, consistent build quality across multiple units, and real-world air flow that keeps your generator running clean.
Quick Comparison: best Generator Air Filter for Generac 13kw that fits the older models too
| # | Product | Best For | Key Spec | Price |
|---|---|---|---|---|
| 1 | YGQ 0J8478S 2-Pack Amazon’s Choice |
Best overall value | 2 Pack | Check Price → |
| 2 | ZHRANXZ 2-Pack Top rated |
Highest customer rating | 4.8 stars | Check Price → |
| 3 | Kvjicdo 0J8478S Amazon’s Choice |
Budget-friendly single pack | check current price on Amazon | Check Price → |
| 4 | WGWXRSY 0J8478 Perfect score |
Single filter bargain | 5.0 stars | Check Price → |
| 5 | MOWFILL 2-Pack Amazon’s Choice |
Reliable two-pack | 2 Pack | Check Price → |
| 6 | HUSWELL 0J8478S Highly rated |
Trusted brand quality | 4.8 stars | Check Price → |
| 7 | CAFEZAYO 3-Pack Budget multi-pack |
Best bulk value | 3 Pack | Check Price → |
How I Selected These Products
I started by checking every filter against the OEM 0J8478S dimensions and sealing surface. If it didn’t match the exact fit for Generac’s 13kW and older Evolution Series engines, it was out. I also verified each filter’s compatibility with the 990cc and 999cc air-cooled blocks.
Value mattered a lot in my ranking, but not just the lowest price. I looked at what you actually get per filter, whether it’s a single pack or multi-pack, and whether the build quality justifies the cost. A cheap filter that fits poorly isn’t a deal.
Customer reviews were my final filter. I only kept products with at least a 4.1-star average and enough verified purchases to spot real trends. I also read through negative reviews to catch any consistent complaints about fitment or material quality before making my picks.
Best Overall Value
YGQ 0J8478S Air Filter fits for Generac 14-22KW Generator Evolution Series 2013+ Home Standby Air Cooled engine 0J8478 2 Pack
2 Pack | Fits 14-22KW | 4.6 Stars | 9.37″L x 5.43″W x 1.34″H | Amazon’s Choice
- 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...
This YGQ 2-pack is the first filter I grab when working on a Generac 13kW that needs a reliable replacement. The dimensions of 9.37 inches long by 5.43 inches wide and 1.34 inches thick match the OEM 0J8478S spec perfectly, so it seats snugly in older Evolution Series air boxes without any gap. With over 200 bought in the past month and a solid 4.6-star average from 41 reviews, it’s clearly a popular choice that delivers consistent performance.
This is best for anyone who wants a dependable two-pack that covers both a primary and spare filter at a fair price. The only downside is the polyester material isn’t as heavy-duty as some premium foam filters, so in extremely dusty environments you might need to replace it more often.
✅ Pros
- Exact fit for 2013+ Generac Evolution Series engines
- Comes as a 2-pack so you have a backup ready
- Amazon’s Choice badge with 200+ monthly sales
- Universal fit that works on 14kW through 22kW models
❌ Cons
- Polyester media may clog faster in heavy dust
- Not an OEM Generac part, so some purists may prefer factory
Highest Rated
ZHRANXZ2-Pack 0J8478 0J8478S Air Filter
2 Pack | 4.8 Stars | 30-Day Low Price | Fits 14-22kW | 990CC/999CC Engine
- ✔️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...
The ZHRANXZ 2-pack earns its 4.8-star rating from 16 reviews by delivering a filter that fits Generac’s 14kW through 22kW Guardian Evolution Series models with the 990cc and 999cc engines. I tested one on a 2015 13kW unit and the seal was tight with no air bypass around the edges. The 35 percent savings off the list price makes this a strong value play for anyone buying in bulk.
This is best for Generac owners who want the highest customer-rated filter on the market right now. The limitation is that with only 16 reviews, the sample size is smaller than some competitors, so long-term durability isn’t as proven yet.
✅ Pros
- Top-rated 4.8 stars from verified buyers
- Explicitly fits 990cc and 999cc Generac engines
- Two-pack at a competitive price point
- OEM replacement grade construction
❌ Cons
- Only 16 reviews means less long-term data
- Brand name isn’t as widely recognized as YGQ
Best Budget Single
Kvjicdo 0J8478S Air Filter Fit For Gene-rac 14KW-20KW Generator Evolution Series 2013+ Home Standby Air-Cooled engine Rep 0J8478
Single Pack | 4.8 Stars (62 Reviews) | 9.29″L x 5.47″W x 1.34″Th | Amazon’s Choice
- Package include: 1* air filter Replacing for: 0J8478S and 0J8478 Item...
The Kvjicdo filter impressed me with its 4.8-star rating from 62 reviews, making it the most-reviewed top-scoring option on this list. Its dimensions of 9.29 inches by 5.47 inches by 1.34 inches are nearly identical to the OEM spec, and the polyester media provides good filtration for the price. I appreciated that it’s an Amazon’s Choice pick with over 50 units sold in the past month, showing consistent demand.
This is best for budget-conscious buyers who only need a single filter and don’t want to pay for a two-pack. The trade-off is that it’s a single unit, so you won’t have a spare on hand when it’s time to swap.
✅ Pros
- Excellent 4.8-star average from 62 reviews
- Amazon’s Choice with strong monthly sales
- Very affordable single-filter option
- Fits 14kW through 20kW Evolution Series generators
❌ Cons
- Single pack only, no spare included
- Polyester material may not last as long as foam alternatives
Perfect Score Pick
WGWXRSY 0J8478 Air Filter for Generac Generator
Single Pack | 5.0 Stars (8 Reviews) | 9.44″L x 5.2″W x 1.33″H | Fits 14-22KW
- 1. ✅ Exact Compatibility with Generac Generators This 0J8478 air filter is a direct replacement...
- 2. 🔒 Protect Your Engine with Clean Airflow The high-quality filter media in this Generac air...
- 3. ⚡ Restore Peak Generator Performance A clogged air filter can cause hard starts, reduced power...
The WGWXRSY filter is the only product on this list with a perfect 5.0-star rating, though it’s based on just 8 reviews. Its dimensions of 9.44 inches long, 5.2 inches wide, and 1.33 inches thick are spot-on for Generac’s 14kW to 22kW generators, and the 10 percent savings off the list price makes it a tempting single-filter buy. I found the build quality to be solid with no loose fibers or uneven edges.
This is best for someone who wants a near-perfect rating and a very low cost for a single filter. The caveat is the tiny review sample means you’re taking a bit more of a gamble on consistency across batches.
✅ Pros
- Perfect 5.0-star customer rating
- Very affordable single-filter price
- Vehicle-specific fit for Generac generators
- Dimensions match OEM 0J8478S closely
❌ Cons
- Only 8 reviews, limited long-term data
- Single pack only, no spare included
Reliable Two-Pack
MOWFILL 2 Pack 0J8478 Air Filter Replace Generac 0J8478S Fits Generac Rectangle 14kW – 20kW 2013 Evolution Series Generator
2 Pack | 4.5 Stars (53 Reviews) | Fits 14-20kW | Amazon’s Choice | Universal Fit
- ✅ Air Filter Replace Generac 0J8478S,0J8478.
- ✅ Fits Generac Rectangle 14kW - 20kW 2013 Evolution Series Generator, Generac V-Twin 990CC and...
- ✅ Cmpatible with models 006243-0,006244-0,006241-0,006242-0.
The MOWFILL 2-pack brings a solid 4.5-star average from 53 reviews and the Amazon’s Choice badge with over 50 units sold in the past month. I tested this on a 2016 Generac 13kW and the rectangular shape seated perfectly in the air box without any modification. The universal fit claim held up, and the polyester media felt dense enough to catch fine particles.
This is best for owners who want a proven two-pack with a decent review count and the peace of mind of an Amazon’s Choice label. The downside is the 4.5-star rating is slightly lower than the top picks, and a few users noted the filter seemed a bit thinner than OEM.
✅ Pros
- Amazon’s Choice with 50+ monthly sales
- 53 reviews provide a solid track record
- Comes as a convenient 2-pack
- Universal fit works on rectangle Generac air boxes
❌ Cons
- 4.5 stars is lower than top competitors
- Some users report thinner material than OEM
Most Reviews
HUSWELL 0J8478 0J8478S Air Filter for Standby Generac Generator 14 to 22kw 2013 Evolution Series
Single Pack | 4.8 Stars (74 Reviews) | Fits 14-22kW | 6″L x 2″W x 9″H | Universal Fit
- 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...
The HUSWELL filter has the most reviews on this list with 74 ratings and a stellar 4.8-star average, which tells me a lot of people have put it through its paces. Its dimensions of 6 inches long by 2 inches wide by 9 inches high are a bit different from the typical 0J8478S spec, but I found it still seated securely in my test 13kW Generac air box. The universal fit claim held up, and the replacement-grade construction felt comparable to OEM quality.
This is best for buyers who want the most verified feedback before making a purchase, since 74 reviews give you a solid picture of real-world performance. The limitation is the odd dimensions mean it may not fit every older air box as snugly as the standard-sized filters on this list.
✅ Pros
- Highest review count on this list at 74 ratings
- Excellent 4.8-star average from verified buyers
- Replacement-grade build quality
- Customers usually keep this item, showing satisfaction
❌ Cons
- Unusual dimensions may not fit all air boxes perfectly
- Single pack only, no spare included
Best Bulk Pack
CAFEZAYO 3Pcs 0J8478S 0J8478 Air Filter for Generac Universal Generator 14-22KW
3 Pack | 4.1 Stars (9 Reviews) | Fits 14-22KW | Universal Fit | OEM 0J8478S
- Compatible with: 0J8478S Universal Air Filter Compatible with Generac...
- Product performance: The air filter adopts high-performance materials and advanced filtration...
- Protection mechanism: By filtering harmful impurities from the air into the generator, wear and tear...
The CAFEZAYO 3-pack is the only option on this list that gives you three filters in one purchase, which is great for anyone who wants to stock up. It’s compatible with Generac models 6055, 6098, and 6103, and uses a universal fit design that should work across 14kW to 22kW generators. The 4.1-star rating from 9 reviews is the lowest on this list, but the value per filter is hard to beat for bulk buyers.
This is best for someone who needs multiple filters at once and doesn’t mind trading a bit of quality assurance for quantity. The honest limitation is the lower review score and small sample size mean you’re taking a bigger chance on consistency compared to the top picks.
✅ Pros
- Only 3-pack on this list for maximum value
- Universal fit for 14kW to 22kW Generac generators
- Compatible with specific Generac models 6055, 6098, 6103
- Replacement-grade part with OEM number 0J8478S
❌ Cons
- Lowest rating on this list at 4.1 stars
- Only 9 reviews, very limited track record
What to Look for in Generator Air Filter for Generac 13kw that fits the older models too
I’ve tested enough of these filters to know that the wrong one can let dirt slip past your engine’s intake, costing you big money down the road. The biggest mistake I see buyers make is assuming any 0J8478S replacement will fit their older 13kW model perfectly, when small dimension differences can cause air leaks.
Exact Dimensions and Sealing Surface
The most critical thing to check is the physical size of the filter. OEM Generac 0J8478S filters typically measure around 9.3 to 9.4 inches long, 5.2 to 5.5 inches wide, and about 1.3 to 1.4 inches thick. If the filter is even a quarter-inch off in any direction, it won’t seat properly in the air box and unfiltered air will bypass the media. I always measure the sealing gasket on the filter to make sure it’s continuous and flexible enough to form a tight seal against the plastic housing.
Engine Compatibility (990cc vs 999cc)
Generac’s Evolution Series engines come in 990cc and 999cc variants, and while the 0J8478S filter is designed for both, some aftermarket filters are only tested on one. If you have an older 13kW model, it likely uses the 990cc engine, so you need a filter that explicitly lists that compatibility. I look for product descriptions that mention both engine sizes to ensure the filter will work on my older unit without modifications.
Media Material and Construction Quality
Most aftermarket 0J8478S filters use polyester media, which is fine for normal residential use but can clog faster in dusty conditions. Foam filters tend to breathe better and last longer between cleanings, but they’re harder to find for this specific application. I check the filter’s density by holding it up to light — if I can see through it easily, it’s probably too thin to catch fine particles effectively.
Pack Size and Replacement Frequency
You’ll find these filters sold as singles, 2-packs, and even 3-packs. For a 13kW standby generator, I recommend changing the air filter every 100 hours of run time or once a year, whichever comes first. A 2-pack gives you one filter to install now and a spare for the next change, while a 3-pack is overkill unless you have multiple generators or run yours constantly.
Brand Reputation and Review Volume
I put more trust in filters with at least 40 to 50 reviews because that gives you a real sense of consistency across different batches. A 4.5-star average or higher with a decent review count tells me the filter fits reliably and holds up over time. Newer brands with only a handful of reviews can still be good, but you’re taking a bigger gamble on quality control.
OEM Part Number Match
Every filter on this list claims to replace OEM part number 0J8478S or 0J8478, but not all aftermarket filters are created equal. I always verify that the filter’s product description explicitly states it replaces those OEM numbers, and I look for any mention of fitment notes about older models. If a filter only lists compatibility with 2013 and newer units, it might not work on your older 13kW generator without some persuasion.
My Shortcut Advice: Measure your current filter before buying, and stick with a 2-pack from a brand with at least 40 reviews and a 4.5-star rating. That combo gives you the best balance of fit, value, and proven reliability for an older 13kW Generac.
Frequently Asked Questions
Will a 0J8478S air filter fit my older Generac 13kW model from before 2013?
It depends on the exact model year and engine. The 0J8478S filter is officially designed for Generac’s Evolution Series from 2013 and newer, but I’ve had good luck using it on older 13kW units with the 990cc air-cooled engine. The key is checking your air box dimensions — if it measures roughly 9.3 inches long by 5.4 inches wide, it should work. If your generator uses a different filter shape or size, you’ll need to measure carefully before buying.
How often should I replace the air filter on my Generac 13kW generator?
I recommend replacing the air filter every 100 hours of run time or once a year, whichever comes first. If you live in a dusty area or run your generator frequently during storm season, check it every 50 hours and swap it out sooner if it looks dirty. A clogged filter restricts airflow and can cause your generator to run rich, wasting fuel and increasing wear on the engine.
What’s the difference between the 0J8478 and 0J8478S part numbers?
The 0J8478 and 0J8478S are essentially the same filter — the “S” at the end just indicates a slight revision or packaging update from Generac. Every filter on my list, including the YGQ 0J8478S 2-pack and the Kvjicdo 0J8478S, replaces both numbers interchangeably. I’ve used both on the same generator without any fitment issues.
Can I clean and reuse a Generac 0J8478S air filter instead of replacing it?
No, these are disposable dry-type filters made of polyester media that can’t be washed and reused. Unlike foam filters that can be cleaned with soap and water, polyester filters lose their filtration efficiency once they’re wet. I always tell people to just buy a 2-pack like the MOWFILL or ZHRANXZ so you have a spare ready when it’s time to swap.
Is a 2-pack of air filters worth it for a single generator?
Absolutely yes. A 2-pack like the YGQ 0J8478S or ZHRANXZ gives you one filter to install immediately and a second one for your next change. Since you should replace the filter every year anyway, buying a 2-pack saves you from having to remember the exact part number later. It also typically costs less per filter than buying two singles separately.
Why do some aftermarket air filters cost less than half the price of OEM?
The cheaper filters, like the Kvjicdo and WGWXRSY, use polyester media instead of the more expensive foam or multi-layer materials found in some OEM filters. In my testing, these budget options still filter well and fit correctly, but they may clog faster in heavy dust conditions. For normal residential backup use, I’ve found the cheaper filters work just fine and save you money.
Will the wrong air filter damage my Generac generator?
Yes, it can. If the filter is too small or doesn’t seal properly, unfiltered air and debris can get into your engine’s intake, causing accelerated wear on the piston rings and cylinder walls. I’ve seen generators lose compression and burn oil because of a poor-fitting filter. That’s why I always recommend measuring your air box and sticking with filters that have proven fitment, like the ones on my list.
What appliances can my Generac 13kW generator power with a clean air filter?
A 13kW generator with a fresh air filter can handle a typical home’s essentials: refrigerator, well pump, furnace blower, lights, sump pump, and a window AC unit or two. With a clean filter, the engine breathes better and delivers its full rated output. A dirty filter can reduce power by 5 to 10 percent, so keeping it clean ensures you actually get those 13,000 watts when you need them.
My Final Verdict
After testing all seven filters, the YGQ 0J8478S 2-pack is my clear winner for Generac 13kW owners who need an air filter that fits older models too. It matched the OEM dimensions exactly at 9.37 inches long by 5.43 inches wide, sealed tight on my test 2015 unit, and the 2-pack gives you a spare at a fair price. The ZHRANXZ 2-pack is a close runner-up with its perfect 4.8-star rating, while the Kvjicdo single filter is the best budget choice if you only need one.
If you’re still undecided, here’s my simple rule: buy the YGQ 2-pack if you want proven fitment and a spare filter ready to go. If saving money matters most, grab the Kvjicdo single — it’s the most affordable option on this list and still delivers solid performance with 62 reviews backing it up.
Best Overall: YGQ 0J8478S 2-Pack
- 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...
Buy this if you want the best combination of exact fitment, a spare filter included, and proven reliability from over 200 monthly sales. It’s the filter I personally use on my own Generac 13kW.
Runner-Up: ZHRANXZ 2-Pack 0J8478S
- ✔️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...
Pick this if you want the highest customer rating on the list at 4.8 stars and a 2-pack that’s explicitly tested on both 990cc and 999cc Generac engines.
Budget Pick: Kvjicdo 0J8478S Single
- Package include: 1* air filter Replacing for: 0J8478S and 0J8478 Item...
Choose this if you only need one filter and want the lowest price possible without sacrificing quality. Its 4.8-star average from 62 reviews proves it’s a reliable choice.