Drop-in panel filter in the airbox. Wix 42096 / FRAM CA3917 fits 1991-2001 XJ. Renix airbox uses a different size.
1991-2001 XJ uses a rectangular panel-style air filter inside the black airbox on the driver-side inner fender. Four spring clips hold the lid down; lift the lid, lift the filter, drop in the new one with the rubber lip facing up. Wix 42096 or FRAM CA3917 are common replacements. K&N reusable washable filters fit (33-2057) but the 4.0L makes no measurable power gain over a clean paper filter and over-oiling K&N filters contaminates the MAP sensor. Check at every oil change; replace every 15-30k or whenever it is visibly dirty. The Renix-era XJ (1987-1990) uses a smaller airbox and round filter element with a different part number. Inspect the airbox snorkel for cracks - it draws fresh air from inside the fender and a torn snorkel is a hidden source of unmetered intake noise.
| Part | Vendor | Est. price |
|---|---|---|
| Wix air filter | RockAuto/NAPA | ~$12 |
| K&N reusable | Summit | ~$55 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.