OE Quality
60-Day Returns

Premium Guard PA99861 Engine Air Filter
Engine Air Filter for Subaru WRX STI
Premium Guard PA99861 is an engine air filter made for direct replacement service on select Subaru performance applications. It is a fitment-specific part for the 2019-2021 Subaru WRX STI and supports routine intake air filtration for street and maintenance use.
Key Features
- Engine air filter for the Subaru WRX STI
- Fits 2019-2021 Subaru WRX STI, N/A
- Replacement part number: PA99861
- Built for air and fuel delivery filter service
- Direct-fit application for confirmed vehicle coverage
Detailed Description
Premium Guard PA99861 is an engine air filter for the 2019-2021 Subaru WRX STI, N/A. It is used to replace the factory air filter element in the intake system and help maintain clean airflow into the engine. If you are searching for a Subaru WRX STI engine air filter, PA99861 provides a vehicle-specific match for the listed model years.
What It Helps Address
- Restricted airflow from a dirty or loaded air filter
- Routine maintenance replacement for the intake system
- Dust and debris entering the engine air path
- Loss of filtration performance from an aged filter
Installation Notes and Tips
Verify the existing filter dimensions and housing style against the vehicle listing before installation. Replace the filter during scheduled maintenance or sooner if the current element is visibly dirty. Confirm fitment for 2019, 2020, and 2021 Subaru WRX STI models before ordering PA99861.
Quality Assurance
Premium Guard PA99861 is cataloged as a direct-fit engine air filter for the confirmed Subaru WRX STI applications listed above. This part cross-references Monroe Shocks & Struts (e.g., 172286, 182286) for the same application.
This part fits 3 vehicles. Search below:
| Year | Make | Model | Liters | Cylinders | Position | Notes |
|---|---|---|---|---|---|---|
| 2021 | Subaru | WRX STI | 2.5L | H4 | N/A | |
| 2020 | Subaru | WRX STI | 2.5L | H4 | N/A | |
| 2019 | Subaru | WRX STI | 2.5L | H4 | N/A |
* Always verify fitment with your vehicle's VIN if unsure. Submodel & trim restrictions may apply.