• Replacing Jeep spark plugs

    This bulletin applies to 2021 Jeep Wrangler and Gladiator vehicles equipped with a 3.6L Pentastar engine.
    March 18, 2025

    This bulletin applies to 2021 Jeep Wrangler and Gladiator vehicles equipped with a 3.6L Pentastar engine.

    If the engine exhibits rough running and cylinder misfire DTCs are present, the original spark plugs may be cracked internally. Due to a known manufacturing issue with the original spark plugs, all six plugs must be replaced even if only one misfire DTC is present.

    Replace with P/N SP225755AA. Follow spark plug gaps listed in the service manual.

    About the Author

    Mike Mavrigian

    Motor Age Editor

    Mike Mavrigian has written thousands of automotive technical magazine articles involving a variety of  specialties, from engine building to wheel alignment, and has authored more than a dozen books that crisscross the automotive spectrum. Mike operates Birchwood Automotive, an Ohio shop that builds custom engines and performs vintage vehicle restorations. The shop also features a professional photo studio to document projects and to create images for articles and books.

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