P0300 — Random/Multiple Cylinder Misfire Detected

P0300 means your engine is misfiring on multiple cylinders without a clear pattern. Common causes are worn spark plugs, failing ignition coils, low fuel pressure, or vacuum leaks.

Cost range: $50–$1,200. Severity: high. Safe to drive? Avoid driving — sustained misfires dump raw fuel into the catalytic converter and can destroy it within a few hundred miles.

Most common causes of P0300

1. Worn spark plugs — First thing to check on any misfire. Plugs over 60k–100k miles are due. ($30–$150)
2. Failing ignition coils — Often one or two coils fail at a time. Swap to confirm. ($50–$400)
3. Vacuum leak — Lean misfire across cylinders. ($10–$200)
4. Low fuel pressure — Weak pump or clogged filter starves all cylinders. ($300–$800)
5. Bad fuel injectors — Carbon-clogged injectors cause widespread misfire. ($200–$600)

Symptoms drivers report with P0300

• Engine shaking
• Loss of power
• Flashing check engine light
• Bad fuel economy