I was scrambling to find a replacement air filter for my Generac 14kW Guardian generator after a long storm season, and the dealer wanted me to wait a week. I decided to try the ZHRANXZ2-Pack 0J8478 0J8478S Air Filter instead, which claims to fit 2013 and newer Evolution Series models with 990cc and 999cc engines.

This two-pack is really for anyone with a Generac 14kW to 22kW standby generator who wants a direct replacement without the OEM price tag. It’s not a performance upgrade—it’s a solid, drop-in part that matches the 0J8478S spec exactly. I was surprised by the build quality for an aftermarket part, and I think you’ll appreciate the value.

What Stands Out — Key Features

• Direct OEM Replacement: This matches the Generac 0J8478S part number exactly, so it drops right into my 14kW Guardian without any trimming or adapters.
• Two-Pack Value: I got two filters in the box, which means I have a spare ready for the next oil change interval without reordering.
• Wide Compatibility: It fits 2013 and newer Generac Evolution and Guardian series generators from 14kW all the way up to 22kW, including models with 990cc and 999cc V-Twin engines.
• Universal Fit Design: The rectangular shape measures 9.44 inches long by 5.47 inches wide and 1.34 inches high, so it also works with Centurion, Siemens, Honeywell, and Eaton standby units.
• Solid Customer Rating: With a 4.8 out of 5 stars from 16 reviews, most buyers like me found it an easy, hassle-free swap.
• 2-Year Manufacturer Warranty: ZHRANXZ backs this with a 2-year warranty, which gave me extra confidence for an aftermarket part.
• FREE Returns: Amazon offers a 30-day return guarantee on this item, so there’s little risk if it doesn’t fit your specific model.

Full Specifications

Pros & Cons — The Honest Take

For the price of two filters, I’m happy with the fit and the warranty, even if the packaging could be sturdier. The pros easily outweigh the single con for me.

⚖️ How Does It Compare?

I picked the MEKILYN 0C8127 and the HUSWELL 0J8478 0J8478S as the closest alternatives to the ZHRANXZ two-pack because they all target the same Generac 0J8478S spec. Here’s how they stack up after my research.

If you need a single filter for an older model that uses the 0C8127 part, go with the MEKILYN. For a single filter with better packaging, the HUSWELL is solid. But for my money, the ZHRANXZ two-pack with its 2-year warranty and direct fit for 14kW-22kW models is the better value for most Generac owners.

How It Actually Performs

Fit and Installation

I swapped the old filter on my Generac 14kW Guardian in about five minutes. The ZHRANXZ filter measures exactly 9.44 inches long by 5.47 inches wide and 1.34 inches high, and it dropped into the rectangular housing without any forcing or trimming. The foam gasket seated evenly against the plastic cover, which surprised me for a universal fit part—I was half expecting to need some weatherstripping tape.

Engine Airflow and Performance

After installing the new filter, I ran a full load test on my 14kW generator for about 45 minutes. The engine didn’t stumble or surge, and the air-fuel mixture seemed stable throughout the test. Since this filter replaces the OEM 0J8478S spec for 990cc and 999cc V-Twin engines, the airflow characteristics are a direct match. I didn’t notice any change in power output or fuel consumption compared to the factory filter.

Build Quality and Materials

The filter media feels dense but not restrictive—similar to the OEM part I pulled out. The cardboard frame is sturdy enough to hold its shape during installation, and the foam gasket is evenly applied around the entire perimeter. My only minor gripe is that the pleats are slightly less uniform than the original Generac filter, but at a 4.8 out of 5 stars rating from 16 buyers, most people seem satisfied with the construction.

Long-Term Durability and Warranty

I’ve had this filter installed for about three weeks with several test runs totaling around four hours of runtime. It shows no signs of collapsing or degrading, and the 2-year manufacturer warranty gives me confidence that ZHRANXZ stands behind their product. For a two-pack that includes a spare, I’m comfortable leaving the second filter in my garage for the next scheduled maintenance interval.

Who Is This Air Filter Best For?

After spending time with the ZHRANXZ2-Pack 0J8478 0J8478S Air Filter, I have a clear picture of who will love it and who should keep shopping. Here’s my honest breakdown.

✅ This Is a Great Fit If You…

• Own a 2013 or newer Generac Guardian Evolution Series generator between 14kW and 22kW with a 990cc or 999cc V-Twin engine.
• Want a spare filter on hand for your next oil change without paying for a second separate purchase.
• Prefer a 2-year manufacturer warranty over the typical 90-day coverage on generic aftermarket filters.
• Appreciate Amazon’s 30-day return guarantee in case the universal fit doesn’t match your specific model.

❌ You Might Want to Look Elsewhere If…

• You have a generator older than 2013 that uses a different OEM part number like 0C8127 instead of 0J8478S.
• You need a filter for a Generac model larger than 22kW, since this only covers up to that output.
• You’re a stickler for OEM-branded parts and don’t trust aftermarket replacements for your standby generator.

For most Generac owners with a 14kW to 22kW unit from 2013 onward, this two-pack is my top recommendation. It’s the filter I’m keeping in my own generator.

Common Issues & Fixes

I ran into a couple of quirks during installation and testing, so here are the fixes that worked for me. These tips should save you some head-scratching.

Filter Doesn’t Sit Flush in the Housing

The problem: The rectangular filter measures 9.44 inches by 5.47 inches, and it felt slightly loose in the housing on my first attempt.

My fix: I pushed the filter all the way to the back of the housing before tightening the cover. The foam gasket compresses enough to create a solid seal once the retaining tabs are locked in place.

Engine Runs Rough After Installation

The problem: My 14kW generator stumbled for a few seconds after I started it with the new filter, which made me nervous.

My fix: I checked that the old filter gasket hadn’t stuck to the housing and created a double seal. After removing the leftover gasket debris, the engine smoothed right out and ran normally.

Filter Media Seems Less Dense Than OEM

The problem: The pleats on the ZHRANXZ filter looked slightly less uniform than the original Generac 0J8478S part I removed.

My fix: I ran a full load test for 45 minutes anyway, and the engine maintained stable power. The filter media is adequate for standard maintenance intervals, so I wouldn’t worry unless you operate in extremely dusty conditions.

Packaging Arrives Crushed

The problem: The box for my two-pack was dented on one corner during shipping, which made me wonder if the filters were damaged.

My fix: I inspected both filters carefully—the cardboard frame and media were fine. If yours arrives damaged, Amazon’s 30-day return guarantee covers it, so don’t hesitate to request a replacement.

Warranty & Support

ZHRANXZ backs this filter with a 2-year manufacturer warranty, which is better than most aftermarket parts. If you have a problem, start with Amazon’s return process since it’s the easiest route for replacements within 30 days of delivery.

My Final Verdict

I honestly think the ZHRANXZ 2-Pack 0J8478 0J8478S Air Filter is a solid choice for anyone with a 2013 or newer Generac Guardian from 14kW to 22kW. It matches the OEM 0J8478S spec, fits the 990cc and 999cc engines perfectly, and the 2-year warranty gives real peace of mind. I’d recommend it to most homeowners, but not if you need a filter for a pre-2013 model or a different part number.

The universal fit means the gasket isn’t quite as precise as the factory part, but for a two-pack at this price point, I’m happy with the performance. I’ll be keeping the spare in my garage for the next maintenance cycle.