Check Engine Light
November 2026 · Lake Wales
2015 Jeep Wrangler
Misfire on Cylinder 4 After a Tune-Up: Do I Need New Coils?
What the customer reported
The vehicle owner reported the check engine light (CEL) was on after a tune-up, with a misfire on cylinder #4. The owner asked for a quote for all new coils.
What we found and did
Further in-depth testing found the cause was a failed engine, internal, rather than the coils. Cylinder 4 had low compression, measured at 50% of spec. The technician ran the diagnosis at our Lake Wales shop and recommended a new engine, which the vehicle owner declined at this time.

