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P0358 Ignition Coil Failure: Water Infiltration Issue in 2005 Ford Expedition XLT 5.4L 3V Triton

Model: Ford Expedition Fault Code: P0358 Posted: 2016-09-04 10:38

My 2005 Ford Expedition XLT with a 5.4L 3V Triton engine is showing fault code P0358, indicating an issue with ignition coil H (cylinder #8 on the driver's side). I'm concerned about how water might be entering the ignition coil area. Could moisture or coolant leaks be contributing to this problem? The vehicle has been experiencing intermittent misfires and the check engine light is on. I've noticed that the spark plug wells near cylinder 6, 7, and 8 appear damp in some conditions.

Related fault codes
P0358
Comments (2)
Anonymous 2016-09-04 13:52

Could you clarify what 'water' refers to? Is it possible this is actually a coolant leak? Are you experiencing any signs of fluid loss or puddling under the vehicle? This ignition coil corresponds to cylinder #8, located on the driver's side.

Anonymous 2021-03-06 17:08

Water leaks from the thermostat housing can run down and pool in the spark plug wells for cylinders 6, 7, and 8. A copper-based stop leak product temporarily resolved the issue, but I still had to replace the spark plugs to restore reliable performance.