An often overlooked service item, the cabin air filter, is super easy to replace in most cars, is normally inexpensive, so is something you should do now!
The cabin filter, while not quite as important to the cars’ performance or handling, makes a massive difference to the experience of being in and driving your car. Those nasty smells that leak in, and especially if you’ve got a mouldy smell from your HVAC, you need to replace your filter ASAP. The good news is it’s generally pretty simple. Here’s how to do it in an Audi A4/S4/RS4 from the B8 and B8.5 models.
First up, remove three plastic thumb screws from below the glovebox, towards the firewall. They might be a tad tight, but you shouldn’t need a single tool for this whole thing. Once the three screws are out, you can remove the foam cover and you’ll see the white plastic cover for the cabin air filter. My cover apparently got pretty brittle, as when I slid it off, two of the clips that lock it in place literally exploded. Fun times. It still fits back on so no big issue. Anyway, you can now pull the old filter out, then slide the new one in and clip the cover back on. Stick the foam back, then the three plastic screws and.. that’s it! Done.
