I’m reaching out regarding my 2015 Chrysler 200C, which has been showing a persistent Cylinder 1 misfire (OBD code P0301). I’ve already completed extensive diagnostics and replaced the following components:
All 4 spark plugs
All 4 ignition coils
Cylinder 1 fuel injector
Valve cover gasket set
PCV valve
Despite these repairs, the misfire remains. I recently performed a compression test with the following results:
Cylinder 1: 0 PSI
Cylinders 2, 3, and 4: 150 PSI each
Additionally, when removing the ignition coil and spark plug from Cylinder 1, there was visible oil contamination — the plug well was not dry as it should be.
Given the 0 PSI reading, I suspect a mechanical issue such as a damaged valve, piston, or timing problem. I’d like to proceed with a leak-down test or any other inspection you recommend to pinpoint the root cause before considering major repairs.
All 4 spark plugs
All 4 ignition coils
Cylinder 1 fuel injector
Valve cover gasket set
PCV valve
Despite these repairs, the misfire remains. I recently performed a compression test with the following results:
Cylinder 1: 0 PSI
Cylinders 2, 3, and 4: 150 PSI each
Additionally, when removing the ignition coil and spark plug from Cylinder 1, there was visible oil contamination — the plug well was not dry as it should be.
Given the 0 PSI reading, I suspect a mechanical issue such as a damaged valve, piston, or timing problem. I’d like to proceed with a leak-down test or any other inspection you recommend to pinpoint the root cause before considering major repairs.
Nov 5, 2025 at 6:20 PM
