Ignition Coil H Primary/Secondary Circuit Malfunction (Cylinder 8)
What does P0358 mean?
The P0358 code means the vehicle's onboard diagnostic system has detected: Ignition Coil H Primary/Secondary Circuit Malfunction (Cylinder 8). This is a moderate severity code.
Common Symptoms
- Engine misfire on cylinder 8
- Rough idle on V8 engine
- Check Engine Light illuminated or flashing
- Reduced power and acceleration
- Poor fuel economy
Probable Causes (Ranked by Likelihood)
- Faulty ignition coil on cylinder 8 Very High
- Worn or fouled spark plug on cylinder 8 High
- Damaged coil connector or wiring High
- PCM coil driver circuit failure for cylinder 8 Moderate
- Spark plug well moisture or oil contamination Low
Step-by-Step Diagnostic Procedure
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Swap cylinder 8 ignition coil with another cylinder and clear codes to test
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Inspect the spark plug on cylinder 8 for wear, fouling, or incorrect gap
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Measure coil resistance -- primary 0.4-2.0 ohms, secondary 6,000-15,000 ohms
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Check the spark plug well for moisture, oil, or debris
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Test PCM coil driver signal at the cylinder 8 connector
Frequently Asked Questions
Can I drive with code P0358?
You can drive short distances with a steady Check Engine Light. If flashing, stop driving to prevent catalytic converter damage from unburned fuel.
Is cylinder 8 always the last cylinder on a V8?
Yes. Cylinder 8 is the rearmost cylinder on bank 2 of a V8 engine. On some trucks, this cylinder can be difficult to access due to its proximity to the firewall.
Can extreme cold weather cause ignition coil failure?
Cold weather does not directly cause coil failure, but it puts more demand on the ignition system. A marginal coil that works in warm weather may fail in cold conditions when the engine requires stronger spark for starting.