Take the knee bolster under the passenger side glove box out and you'll see the air filter box all the way against the firewall. You'll need a 25 or 30T torx driver to get the screws out from the bottom of it to replace the filter. There are two slots for the filter (2 different types depending on what kind of ECC you have). Take out the filter and eye-ball it, getting the same replacement. fcpgroton.com has both kinds...either slimmer, cheaper or thicker kind with activated carbon and plastic housing built onto the filter. The thicker one is about $7 or $8 more than the skinnier one. I hope this helps.
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1998 S70 T5 Emarald Green Metallic (125K), 2004 V70 2.5T Ruby Red (45K), Previous Owner of Black '94 850 Turbo Wagon (Sold at 140K and miss her). My cars have been running so well lately they've got me worried.