P0359 moderate

Ignition Coil I Primary/Secondary Circuit Malfunction (Cylinder 9)

The P0359 code means the vehicle's onboard diagnostic system has detected: Ignition Coil I Primary/Secondary Circuit Malfunction (Cylinder 9). This is a moderate severity code.

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Keep driving?: Short distances only
DIY difficulty: moderate
Estimated cost: $50 - $400 (parts and labor)

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Common Symptoms

Engine misfire on cylinder 9
Rough idle on V10 engine
Check Engine Light illuminated or flashing
Reduced power
Exhaust has fuel smell

Probable Causes (Ranked by Likelihood)

Faulty ignition coil on cylinder 9 Very High
Worn or fouled spark plug on cylinder 9 High
Damaged coil connector or wiring High
PCM coil driver circuit failure for cylinder 9 Moderate
Coil boot deterioration from heat exposure Low

Step-by-Step Diagnostic Procedure

Swap cylinder 9 ignition coil with another cylinder and clear codes to test
Inspect the spark plug on cylinder 9 for wear, fouling, or damage
Measure coil resistance and compare to specification
Check the coil connector and boot for heat damage or carbon tracking
Test PCM coil driver signal at the connector

Frequently Asked Questions

Can I drive with code P0359?

You can drive short distances. On a V10 engine, losing one cylinder still leaves nine working, but the misfire should be repaired to protect the exhaust system.

What vehicles have a cylinder 9?

Only V10 engines have a cylinder 9. The most common are the Ford Triton 6.8L V10 found in F-250/F-350 trucks and E-Series vans, and the Dodge Viper V10.

Are V10 spark plugs more difficult to change?

Ford V10 engines are known for spark plug issues, including plugs that can break during removal due to carbon buildup in the threads. Using anti-seize compound during installation and changing plugs at recommended intervals helps prevent this.