Ignition Coil D Primary/Secondary Circuit Malfunction (Cylinder 4)
What does P0354 mean?
The P0354 code means the vehicle's onboard diagnostic system has detected: Ignition Coil D Primary/Secondary Circuit Malfunction (Cylinder 4). This is a moderate severity code.
Common Symptoms
- Engine misfire on cylinder 4
- Rough idle and vibration
- Check Engine Light illuminated or flashing
- Reduced power and hesitation
- Poor fuel economy
Probable Causes (Ranked by Likelihood)
- Faulty ignition coil on cylinder 4 Very High
- Worn or fouled spark plug on cylinder 4 High
- Damaged coil connector or wiring High
- PCM coil driver circuit failure for cylinder 4 Moderate
- Water intrusion in spark plug well Low
Step-by-Step Diagnostic Procedure
-
Swap cylinder 4 ignition coil with another cylinder -- if the misfire code moves, the coil is faulty
-
Inspect the spark plug on cylinder 4 for wear, oil fouling, or damage
-
Measure coil resistance -- primary 0.4-2.0 ohms, secondary 6,000-15,000 ohms
-
Check the spark plug well for water or oil contamination that may cause misfires
-
Test the PCM coil driver signal at the connector
Frequently Asked Questions
Can I drive with code P0354?
You can drive short distances with a steady Check Engine Light. A flashing light means catalytic converter damage is imminent -- stop driving immediately.
Can oil in the spark plug well cause P0354?
Yes. A leaking valve cover gasket can allow oil to pool around the coil boot in the spark plug well, causing the coil to short out or the spark to arc to ground instead of the plug.
How long do ignition coils typically last?
Ignition coils typically last 80,000-100,000 miles. However, they can fail earlier if spark plugs are not replaced on schedule, as worn plugs force coils to work harder.