P0351 — Ignition Coil A Primary/Secondary Circuit Malfunction

P0351 means the ECM detected an electrical fault in ignition coil 1's circuit. On coil-on-plug engines it's usually the coil itself or its connector.

Cost range: $80–$500. Severity: high. Safe to drive? No if the check engine light is flashing — unburnt fuel will damage the catalytic converter.

Most common causes of P0351

  1. Failed ignition coil — Swap with a neighbouring cylinder to confirm the fault moves. ($80–$350)
  2. Damaged coil connector — Brittle plastic clips break and lose contact under vibration. ($40–$150)
  3. Chafed coil harness wiring — Runs along the valve cover and rubs through. ($80–$250)
  4. Carbon-tracked spark plug boot — Arcing to ground. Replace boots with plugs. ($30–$120)

Symptoms drivers report with P0351