P0351

Ignition Coil "A" Primary/Secondary Circuit Malfunction

OBD-II diagnostic trouble code P0351indicates a fault detected by the vehicle's onboard computer. This code applies to all OBD-II compliant vehicles and should be addressed promptly to avoid potential engine or emissions system damage.

Severity Level 4 — Serious

This code indicates a serious issue that can cause noticeable driveability problems and potential engine damage if not addressed. The vehicle should be taken to a mechanic as soon as possible. Extended driving is not recommended.

Common Symptoms

• Check Engine Light on (may flash under load)
• Engine misfire, rough running, shaking
• Loss of power and acceleration
• Poor fuel economy
• Engine may not start if coil is completely dead (COP systems)

Possible Causes

• Faulty ignition coil — internal winding short or open circuit from heat stress
• Damaged wiring or loose connector at coil — broken wire at connector from engine vibration
• Blown ignition coil fuse (shared for multiple coils, if blown all on that circuit fail)
• Faulty ignition control module (ICM) or PCM coil driver transistor failed
• Spark plug with excessive gap forcing coil to work harder and overheat

Common Fixes

• Replace ignition coil "A" (cylinder 1 on most engines, check firing order) ($50-200)
• Repair damaged wiring or connector at coil ($30-150)
• Replace blown ignition fuse ($1-5)
• Replace spark plugs if worn — excessive gap damages coils ($40-200 for set)
• Replace PCM if internal driver failed (rare, $500-1500)

Estimated Repair Cost

These are estimated costs based on generic repair data. Actual costs may vary depending on your vehicle, location, and labor rates.

Explore Repair Costs

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