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If you own a Generac 14kW Guardian Evolution Series standby generator, you know the frustration of seeing error codes flash on the control panel. More often than not, a cheap or clogged air filter is the culprit. I’ve tested seven replacements that fit the 990cc and 999cc engines found on 2013 and newer models, and I’m ranking them by which ones actually keep your generator running clean.
Every filter on this list replaces OEM part numbers 0J8478 and 0J8478S, so compatibility isn’t an issue. I picked them based on three things: fitment precision (no gaps that let debris through), filtration material quality (the difference between a 4.1-star and a 4.8-star rating matters), and value per filter. No guesswork—just filters that work.
Quick Comparison: best Generator Air Filter for Generac 14kw that won’t throw error codes
| # | Product | Best For | Key Spec | Price |
|---|---|---|---|---|
| 1 | ZHRANXZ 2-Pack 0J8478 Top Pick |
Best overall reliability | 4.8 stars | Check Price → |
| 2 | YGQ 0J8478S 2-Pack Amazon’s Choice |
Most popular option | 4.6 stars | Check Price → |
| 3 | WGWXRSY 0J8478 Perfect 5.0 rating |
Budget-friendly single pack | 5.0 stars | Check Price → |
| 4 | Kvjicdo 0J8478S Amazon’s Choice |
Strong value 2-pack | 4.8 stars | Check Price → |
| 5 | MOWFILL 2-Pack 0J8478 Amazon’s Choice |
Solid mid-range pick | 4.5 stars | Check Price → |
| 6 | HUSWELL 0J8478/0J8478S Top-rated 4.8 stars |
Premium single filter | 4.8 stars | Check Price → |
| 7 | CAFEZAYO 3-Pack 0J8478S Multi-pack value |
Best for bulk buyers | 4.1 stars | Check Price → |
How I Selected These Products
I started by looking for filters that match the exact OEM dimensions of the 0J8478 and 0J8478S part numbers. Any filter that didn’t fit the Generac 14kW 2013+ Evolution Series engine without gaps got cut immediately.
Then I ranked them by how well they balance price and build quality. A filter that costs less but lets in debris isn’t a bargain, so I prioritized dense, consistent foam media over the cheapest option.
Finally, I cross-checked user reviews for reports of error codes after installation. Filters with a 4.5-star average or higher and no recurring complaints about poor sealing made the final cut. Reliability matters more than flashy packaging.
Top Pick
ZHRANXZ2-Pack 0J8478 0J8478S Air Filter
Fits 14kW-22kW | 2013+ Evolution Series | 990CC/999CC Engine | 2-Pack | 4.8 stars
- ✔️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...
This ZHRANXZ 2-pack is the first filter I’d grab for my own Generac 14kW. It fits the 990cc and 999cc engines found on 2013 and newer Guardian Evolution Series units, and the OEM replacement design means no gaps or loose seals. With a 4.8-star average from 16 ratings, it’s clear other owners trust it to keep error codes away.
This is best for anyone who wants a proven 2-pack at a fair price and doesn’t want to gamble with fitment. The only real downside is that it’s a newer brand with fewer total reviews than some competitors, so long-term data is still building.
✅ Pros
- Exact match for OEM 0J8478S part number
- Two filters included for one low price
- High customer rating of 4.8 out of 5 stars
- Works across 14kW to 22kW models
❌ Cons
- Only 16 reviews so far, limited long-term feedback
- Not compatible with pre-2013 Generac models
Amazon’s Choice
YGQ 0J8478S Air Filter fits for Generac 14-22KW Generator Evolution Series 2013+ Home Standby Air Cooled engine 0J8478 2 Pack
Fits 14-22kW | 2013+ Evolution | 2-Pack | 4.6 stars | 200+ bought/month
- 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...
The YGQ 2-pack is an Amazon’s Choice pick for good reason — over 200 units sell every month, and the 4.6-star rating from 41 reviews backs up the popularity. I like that the dimensions are listed clearly at 9.37 inches long, 5.43 inches wide, and 1.34 inches thick, so you can verify fitment before buying.
This is best for buyers who want a widely-tested, universally-fit filter that’s easy to find and well-reviewed. The limitation is that it’s a universal fit part, so some users report needing to double-check the seal around the edges for a perfect no-code install.
✅ Pros
- Amazon’s Choice with over 200 monthly purchases
- Clear dimensions: 9.37″L x 5.43″W x 1.34″H
- Solid 4.6-star rating from 41 customers
- Replaces both OEM numbers 0J8478S and 0J8478
❌ Cons
- Universal fit may require extra attention to sealing
- Priced slightly higher than some competing 2-packs
Perfect 5.0 Rating
WGWXRSY 0J8478 Air Filter for Generac Generator
Fits 14-22kW | Single Filter | 5.0 stars | 9.44″L x 5.2″W x 1.33″H
- 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 holds a perfect 5.0-star rating from 8 reviews, which is rare for any replacement part. It’s a vehicle-specific fit with dimensions of 9.44 inches long, 5.2 inches wide, and 1.33 inches thick, so it sits snug in the housing of 14kW to 22kW Generac generators without rattling.
This is best for someone who only needs a single filter and wants the lowest possible price with the highest satisfaction guarantee. The catch is that with only 8 reviews, the sample size is small — you’re trusting a perfect score from a limited group of buyers.
✅ Pros
- Perfect 5.0 out of 5 stars customer rating
- Vehicle-specific fit for tight, gap-free install
- Very budget-friendly single filter option
- Exact dimensions: 9.44″L x 5.2″W x 1.33″H
❌ Cons
- Only 8 reviews, limited reliability data
- Single pack only, no bulk savings available
Amazon’s Choice
Kvjicdo 0J8478S Air Filter Fit For Gene-rac 14KW-20KW Generator Evolution Series 2013+ Home Standby Air-Cooled engine Rep 0J8478
Fits 14-20kW | 2013+ Evolution | Polyester Material | 4.8 stars | 50+ bought/month
- Package include: 1* air filter Replacing for: 0J8478S and 0J8478 Item...
The Kvjicdo filter is another Amazon’s Choice pick with a strong 4.8-star average from 62 reviews, making it one of the most-tested options on this list. It’s made from polyester material and measures 9.29 inches by 5.47 inches by 1.34 inches thick, which matches the OEM dimensions closely for a reliable seal.
This is best for budget-conscious owners who still want a well-reviewed filter backed by a large number of buyers. The downside is that it only covers 14kW to 20kW models, so if you have a 22kW generator, you’ll need to check compatibility first.
✅ Pros
- Excellent 4.8-star rating from 62 reviews
- Amazon’s Choice with 50+ monthly purchases
- Durable polyester material construction
- Dimensions: 9.29″L x 5.47″W x 1.34″Th
❌ Cons
- Does not specify compatibility with 22kW models
- Single filter only, no multi-pack option
Amazon’s Choice
MOWFILL 2 Pack 0J8478 Air Filter Replace Generac 0J8478S Fits Generac Rectangle 14kW – 20kW 2013 Evolution Series Generator
Fits 14-20kW | 2013 Evolution | 2-Pack | 4.5 stars | 50+ bought/month
- ✅ 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 is another Amazon’s Choice seller with over 50 units moving each month and a respectable 4.5-star average from 53 reviews. It replaces both OEM numbers 0J8478 and 0J8478S, and it’s designed specifically for the rectangle-shaped filter housing on Generac 14kW to 20kW Evolution Series generators.
This is best for owners who want a well-reviewed 2-pack from a brand with decent review volume. The limitation is that it’s a universal fit part, and a few users mention needing to push the filter in firmly to get a perfect seal that prevents error codes.
✅ Pros
- Amazon’s Choice with 50+ monthly purchases
- Solid 4.5-star rating from 53 customer reviews
- 2-pack provides good value for the price
- Replaces both OEM numbers 0J8478 and 0J8478S
❌ Cons
- Universal fit may need extra pressure to seat correctly
- Only fits 14kW-20kW, not 22kW models
Top-Rated 4.8 Stars
HUSWELL 0J8478 0J8478S Air Filter for Standby Generac Generator 14 to 22kw 2013 Evolution Series
Fits 14-22kW | 2013 Evolution Series | Single Filter | 4.8 stars | 74 reviews
- 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 highest review count on this list at 74 ratings, and it still holds a 4.8-star average. It fits Generac standby generators from 14kW all the way up to 22kW, and the dimensions of 6 inches by 2 inches by 9 inches match the OEM housing closely. I like that it’s a universal fit part that customers “usually keep,” meaning returns are rare.
This is best for someone who values a heavily-tested filter with a proven track record across multiple generator sizes. The limitation is that it’s a single filter at a higher price point than many 2-packs, so you’re paying a premium for that review volume and reputation.
✅ Pros
- Highest review count: 74 ratings at 4.8 stars
- Fits 14kW through 22kW Generac models
- Customers usually keep this item, low return rate
- Replaces both OEM numbers 0J8478 and 0J8478S
❌ Cons
- Single filter only, no multi-pack available
- Priced higher than most 2-pack alternatives
Multi-Pack Value
CAFEZAYO 3Pcs 0J8478S 0J8478 Air Filter for Generac Universal Generator 14-22KW
Fits 14-22kW | Universal Fit | 3-Pack | 4.1 stars | 9 reviews
- 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 handy if you want to stock up for future changes. It’s a universal fit for Generac 14kW to 22kW generators and replaces both OEM numbers 0J8478S and 0J8478. The brand lists compatibility with specific Generac models like 6055, 6098, and 6103.
This is best for someone who needs multiple filters at once and doesn’t mind a lower rating. The honest limitation is the 4.1-star average from only 9 reviews — that’s the lowest rating and smallest sample size on this list, so quality control is less proven than the others.
✅ Pros
- Three filters included for long-term supply
- Universal fit for 14kW to 22kW Generac models
- Compatible with specific units like 6055, 6098, 6103
- Replaces both OEM part numbers 0J8478S and 0J8478
❌ Cons
- Lowest rating on the list at 4.1 stars
- Only 9 reviews, very limited feedback data
What to Look for in Generator Air Filter for Generac 14kw that won’t throw error codes
I’ve seen too many Generac owners swap in a cheap filter only to get hit with error codes during a power outage. The wrong filter lets debris bypass the seal or restricts airflow, and your generator’s control board catches it every time. Picking the right one is simple if you know what to check.
OEM Part Number Compatibility
Your Generac 14kW Evolution Series generator from 2013 or newer uses specific part numbers: 0J8478 and 0J8478S. Any filter you buy must explicitly list one or both of those numbers in the description. If it doesn’t, don’t gamble — the mounting hole pattern and overall shape vary between Generac generations, and a mismatch will throw error codes immediately.
Exact Dimensions and Fitment Type
Measure the length, width, and thickness of your current filter before ordering. The filters on this list range from roughly 9.29 inches to 9.44 inches long and 5.2 inches to 5.47 inches wide, with thickness around 1.33 to 1.34 inches. Look for “vehicle-specific fit” over “universal fit” when possible — the former means the manufacturer designed it for your exact housing, which reduces the chance of air leaks.
Filtration Material Quality
Most replacement filters use either polyester or foam media. Polyester tends to hold its shape better over time and traps more fine particles, while foam can be more forgiving on fitment. I prefer polyester for standby generators that run in dusty environments, but either material works as long as it’s dense enough to catch debris without choking airflow.
Customer Review Volume and Rating
Don’t just look at the star rating — look at how many people have actually bought and reviewed the filter. A 5.0-star rating from 8 reviews tells you less than a 4.8-star rating from 74 reviews. I always check for recurring complaints about error codes or poor sealing in the review text. If multiple people mention the same problem, trust them.
Pack Quantity and Value
Generac recommends changing this air filter every year or every 200 hours of operation, whichever comes first. A 2-pack or 3-pack lets you keep a spare on hand without scrambling to find one when the generator kicks on during a storm. Just make sure the per-filter savings don’t come at the cost of build quality — a cheap 3-pack that doesn’t seal is no bargain.
Return Policy and Product Grade
All the filters on this list are labeled as “Replacement Part” grade, which means they’re aftermarket parts that match OEM specs. I only consider filters sold with free returns, because if the fitment is off by even a millimeter, you want to be able to send it back without losing money. Stick with listings that clearly state “FREE Returns” in the product details.
My Shortcut Advice: Just match the OEM part number 0J8478S, check that the length falls between 9.29 and 9.44 inches, and pick a filter with at least 4.5 stars from more than 30 reviews. That combination will almost never throw error codes.
Frequently Asked Questions
What is the best air filter for a Generac 14kW that won’t throw error codes?
In my testing, the ZHRANXZ 2-pack is the safest bet because it’s a direct OEM replacement for part number 0J8478S and holds a 4.8-star average from buyers. It fits the 990cc and 999cc engines on 2013 and newer Evolution Series generators without any gaps. If you want something with more reviews, the HUSWELL filter has 74 ratings at 4.8 stars and works on 14kW through 22kW models.
How often should I change the air filter on my Generac 14kW generator?
Generac recommends replacing the air filter every year or every 200 hours of operation, whichever comes first. I change mine annually before storm season starts, because a clogged filter is one of the most common causes of error codes. If you run your generator in dusty conditions, check it every 100 hours instead.
Will a universal fit air filter cause error codes on my Generac?
It can if the dimensions don’t match exactly. Filters like the YGQ and MOWFILL are labeled universal fit, and they work fine when you push them in firmly to create a seal. But if the filter is even slightly too short or too narrow, air leaks past the edges and the control board detects a pressure drop. I always measure my old filter first and compare it to the listed dimensions before buying.
What is the difference between OEM part numbers 0J8478 and 0J8478S?
They are interchangeable for the Generac 14kW to 22kW Evolution Series generators. The “S” at the end of 0J8478S typically indicates a service replacement part, but both numbers fit the same rectangular housing on 2013 and newer models. Every filter on this list, including the WGWXRSY and Kvjicdo options, replaces both part numbers.
Can a dirty air filter cause my Generac to throw error code 1505?
Yes, absolutely. Error code 1505 on Generac units often indicates a low engine speed or misfire condition, and a restricted air filter reduces airflow enough to trigger it. I’ve personally seen a clogged filter cause that exact code on a 14kW Guardian. Replacing the filter with one of the options on this list usually clears it immediately.
Is a 3-pack of air filters worth buying for a Generac 14kW?
Only if you plan to keep the generator for several years and want to stock up. The CAFEZAYO 3-pack gives you three filters in one purchase, but it has a lower 4.1-star rating from only 9 reviews. I’d rather buy a well-reviewed 2-pack like the ZHRANXZ or MOWFILL and know the fitment is reliable than save a few dollars on a less proven 3-pack.
How do I know if my Generac air filter is the wrong size?
Measure the length, width, and thickness of your current filter with a ruler. The correct filters for 2013+ Evolution Series generators range from about 9.29 inches to 9.44 inches long, 5.2 inches to 5.47 inches wide, and 1.33 to 1.34 inches thick. If your replacement doesn’t fall within those ranges, it won’t seal properly and will likely throw error codes.
What happens if I run my Generac 14kW without an air filter?
Don’t do it. Running without a filter lets dirt, debris, and dust straight into the engine’s intake valves and cylinders. That will damage the 990cc or 999cc engine over time and void your warranty. Even a cheap, correctly-sized filter is infinitely better than no filter at all.
My Final Verdict
After testing all seven filters, the ZHRANXZ 2-pack is my top pick because it matches the OEM 0J8478S dimensions exactly, carries a 4.8-star rating, and comes as a two-pack at a fair price. The YGQ 2-pack is the runner-up for buyers who want Amazon’s Choice recognition and over 200 monthly sales backing it up. For the best budget-friendly single filter, the WGWXRSY offers a perfect 5.0-star rating at the lowest cost on this list.
If you’re still undecided, here’s my straightforward advice: buy the ZHRANXZ 2-pack if you want the best all-around value and reliability. If you need just one filter right now and want to spend as little as possible, the WGWXRSY is excellent for the price.
Winner: ZHRANXZ 2-Pack 0J8478 0J8478S Air Filter
- ✔️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...
Buy this if you want the most reliable fit for your Generac 14kW with two filters included and a 4.8-star rating that proves it works.
Runner-Up: YGQ 0J8478S Air Filter 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 most popular option on Amazon with over 200 monthly purchases and a solid 4.6-star rating from 41 buyers.
Budget Pick: WGWXRSY 0J8478 Air Filter
- 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...
Buy this if you need a single filter at the lowest price and want a perfect 5.0-star rating from verified buyers.