Most of the maintenance between the 986, 987 and Cayman 987 is very similar and the instructions work for most, but the 981 is a different animal altogether.
Following is the step-by step for a complete cabin air filter service for your 981 Boxster, 981 Boxster S, 981 Cayman, 981 Cayman S or 981 Cayman GTS.
The illustrating photos are from a Cayman GTS but they will be very similar for the Boxster as well.
Part Number: 991.573.623.00 Cabin Filter - Charcoal
Part Number: 991.572.371.00 Pre-Filter
First, the easier one.
It’s located in the front, under the battery trim cover.
Open the front hood and lift the battery trim cover’s front edge.
Take the yellow strap and hang from the hood’s center opening.
The pre-filter housing is located on the right (passenger) side of the battery. The lid is secured with plastic tabs. Move them open with your finger and lift the lid to expose the pre-filter
Now you can just pull the filter straight up.
It forms a curve in the housing but will straighten out as you pull up on its top edge.
Replace with the new pre-filter and close back up in reverse order.
Now it’s time to replace the cabin filter itself which is located in the passenger’s footwell, just under the glove compartment, in front of the airbag.
You need to remove the foam trim which is secured with three plastic fasteners.
Use a stubby flat-bladed screwdriver for easier access.
With the foam trim out of the way you will fee the cabin filter housing. Open the cover (from the bottom) and pull out the filter.
Replace the filter and re-assemble in reverse order.
981 Cabin Air Filters