Subaru 16546 AA10A vs. Subaru 16546 AA12A vs. Denso 143-3199

Superseded together?

What’s the different between the Subaru engine air filters ending in AA10A and AA12A? If you look in the Worldpac catalog, searching for an AA10A will bring up an AA12A and Denso 143-3199.

However, if you call your Subaru dealer, they’ll tell you they are two different air filters.

Who’s right?

All Denso branded but not all the same

The quick answer is that all 3 filters will fit perfectly in your car, provided it requires a 16546AA10A or 16546AA12A.

All 3 filters are made by Denso. However, they’re not really the same. The dealership is correct. One of the 3 filters is better than the others, at least in my opinion.

Ooh! A fancy package!

Denso is a brand sold to professional mechanics and consumers in the know. Since it’s a consumer product, a little more effort goes into the packaging. Where Subaru opts for a plain white box like a 1980s generic product, Denso has a fully color printed box with lots of marketing.

Denso makes many of the parts for Subaru, Honda, and Toyota. So, you may notice Denso markings on your Genuine Parts, as is the case with these filters.

However, as we’re about to find out, Denso isn’t always the same as Genuine Parts.

AA10A vs. AA12A

To the right is a Genuine Subaru AA10A (right) and AA12A (left). They are dimensionally identical, but as you can see, the AA10A has orange filter media and more filter paper. More filter paper is better because it means more surface area which means better flow and a longer service life.

The AA12A has 14 folds. The AA10A has 23 folds. Based on this we can estimate the AA10A has an additional 64% more filter media.

One note is that on some applications (the 2010 Forrester for instance), the turbo model gets the 12A and the standard gets the 10A. It’s possible that the 12A flows better, even though it has less media.

AA12A vs 143-3199

Now for Subaru 16546 AA12A vs Denso 143-3199. The Denso is on the right and the Subaru is on the left. These two are close to identical. They’re obviously built from the same design, but not in the same factory. The Subaru filter is built in the USA. The Denso filter has no country-of-origin marks on the box or filter, but I’d wager it wasn’t built in the US or Japan.

The quality is better on the Subaru filter. You’ll notice that the gasket is a bit crooked on the Denso and the ejector and other die marks are sloppier.

As far as function, I think they will both perform the same, the Subaru will just look prettier while doing it. Both have 14 folds, and the filter media looks the same to me.