Honda Civic Engine Air Filter K&N (88-91)

Honda Civic Engine Air Filter K&N (88-91)

Your 1988-1991 Civic uses a paper engine air filter in the factory airbox. When that filter is dirty, K&N 33-2025 is the washable Honda Civic engine air filter that drops in the same box on the hatch, sedan, and wagon.

Read the year on the door jamb, because 1992 is a new Civic and a new panel. This same filter also fits the 1988-1991 CRX DX, HF, and Si. Those cars share this airbox with the Civic.

What It Is and Why It Works

The trade here is paper against oiled cotton, and it is worth being honest about both sides. Honda paper filters fine, and you bin it every service. This is four layers of oiled cotton gauze that you wash and keep for as long as you own the car. K&N rates the media at up to 99 percent overall efficiency and says it only needs cleaning every 75,000 miles under normal highway driving, both per manufacturer. It ships pre-oiled, so it goes straight in the box out of the bag.

What you give up is the oil-free part, and that matters if a hot-wire sensor sits in the intake. Over-oil a cotton filter and you can put oil film on that sensor, and then you are chasing a driveability problem that the filter caused. Use the right amount, which K&N puts at 0.66 oz for this panel, and keep the oil off the gasket face. If you would rather not think about oil at all, buy a dry filter instead and stop reading here. If you will clean it properly, this is the correct 1988-1991 panel and it is the last one you buy for the car.

Set your expectations on power honestly. A panel filter sitting in a stock airbox does not make horsepower you can feel. The restriction on a D15 or D16A6 is the box, the snorkel and the head, not the element inside it. Buy this because you are tired of replacing paper, not because you expect a dyno result. K&N backs stock-replacement High-Flow filters with a No-Hassle Lifetime Limited warranty, limitations apply.

Specs

Fitment

Factory engine airbox only, and it is not a cabin filter. These cars never had a glovebox cabin filter. Hatch, sedan, wagon, and CRX share this panel on both the 1.5 and the 1.6. A 1992 Civic is the next generation. That car takes K&N 33-2047 and Honda 17220-P07-000. If you are not sure what you are holding, measure the paper: 8.625 by 7.25 by 0.875 inches is this one. 8.375 by 7.438 by 0.75 inches is the 1992-1995 panel. This filter does not fit a 1987 Civic. Official K&N 1987 Civic 1.5 pages do not list 33-2025.

What to Know Before You Buy

Buy the right chemicals with it. This filter is oiled, so when it comes time to clean it you need K&N cleaner and K&N oil, and their 99-5000 service kit has both in one box. Dry-filter cleaner is the wrong bottle for this media, so if you have an AEM DryFlow spray on the shelf from another car, leave it there. Wash it, let it dry all the way, oil it with 0.66 oz, done. The most common way people ruin one of these is soaking it and putting it back in wet, or dumping a whole bottle on an 0.875 in panel.

Confirm the year before you order, not just the Civic badge. If the car is 1992-1995, this is the wrong SKU. That generation takes K&N 33-2047. If the car is 1984-1987, this is also the wrong SKU. And if the car already has a K&N intake kit on it, that kit came with its own conical filter and this panel does nothing for you. 33-2025 stays in the factory airbox.

While the airbox lid is off, spend two minutes on the rest of it. Check that the lid gasket is seated flat and the clips all latch evenly, because a warped lid on a Civic this age leaks more air past the filter than any element flows through it. Look at the breather hose that dumps into this box too. A soaked elbow puts oil mist upstream of a brand new filter, and then people blame the filter. Snug the intake tube clamp on the way back together. That is the whole job.