Ignition Coil G Primary/Secondary Circuit Malfunction (Cylinder 7)
What does P0357 mean?
The P0357 code means the vehicle's onboard diagnostic system has detected: Ignition Coil G Primary/Secondary Circuit Malfunction (Cylinder 7). This is a moderate severity code.
Common Symptoms
- Engine misfire on cylinder 7
- Rough idle on V8 engine
- Check Engine Light illuminated or flashing
- Reduced power
- Exhaust has fuel smell
Probable Causes (Ranked by Likelihood)
- Faulty ignition coil on cylinder 7 Very High
- Worn or fouled spark plug on cylinder 7 High
- Damaged coil connector or wiring High
- PCM coil driver circuit failure for cylinder 7 Moderate
- Spark plug well contamination Low
Step-by-Step Diagnostic Procedure
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Swap cylinder 7 ignition coil with another cylinder and clear codes to test
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Inspect the spark plug on cylinder 7 for wear, fouling, or damage
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Measure coil resistance values and compare to specification
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Check coil connector and spark plug well for contamination
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Test PCM coil driver signal at the connector
Frequently Asked Questions
Can I drive with code P0357?
You can drive short distances. On V8 engines, losing one cylinder is noticeable but the engine will still run. Repair promptly to prevent catalytic converter damage.
Where is cylinder 7 on a V8 engine?
Cylinder numbering varies by manufacturer. On GM V8s, cylinder 7 is typically on the driver side (bank 2). On Ford V8s, cylinder 7 is on the passenger side. Always check your service manual.
Can a bad coil damage the catalytic converter?
Yes. When a coil fails, unburned fuel from the misfiring cylinder enters the exhaust and can overheat and damage the catalytic converter. A flashing Check Engine Light specifically warns of this condition.