P0307 — Cylinder 7 Misfire Detected

P0307 means cylinder 7 is misfiring — a V8-only code. Check spark plug and coil first; swap components with a neighbouring cylinder to confirm before buying parts.

Cost range: $50–$1,200. Severity: high. Safe to drive? No with a flashing light. Catalytic converter damage begins almost immediately.

Most common causes of P0307

1. Worn spark plug — Cheapest fix; check the gap and electrode wear. ($20–$150)
2. Failed coil — Swap-test with cylinder 5 or 8. ($80–$350)
3. Injector fault — Balance-test the bank. ($200–$700)
4. Collapsed lifter or valvetrain wear — Common on high-mileage cylinder-deactivation V8s. ($900–$3,000)

Symptoms drivers report with P0307

• Engine shake
• Flashing CEL
• Ticking noise
• Power loss