P0300 on Honda: Random or Multiple Cylinder Misfire Detected
Severity: 3 of 4
Park it if the check engine light is flashing or the engine is shaking. A flashing light means misfires severe enough to damage the catalytic converter and in extreme cases cause an exhaust fire. If the light is steady and the misfire is mild, drive only as far as needed to get it diagnosed, gently and without heavy loads.
Estimate range covers the repairs listed below; see the cost breakdown. A flashing check engine light, a hot temperature gauge, or brakes that feel different mean stop driving and get help.
What P0300 usually means on a Honda
Honda has issued warranty extensions on some engines for misfires (P0301 to P0304) caused by piston ring sticking that lets oil foul the spark plugs. The repair can include a PCM update, new plugs, and piston ring replacement. Ask a dealer to check your VIN.
Valve clearance that has tightened over time can also cause misfires on many Honda engines.
Most likely causes on Honda vehicles
- Fouled spark plugs
- Ignition coils
- Tight valve clearance
- Piston ring sticking covered by some warranty extensions
Order reflects cost and likelihood in general; your vehicle may differ. Confirm with testing before buying parts.
Honda specific tips
- Ask the dealer about bulletins and extended warranties.
- Valve adjustment is part of Honda maintenance on many engines.
Estimated repair cost
This is an estimate, built from typical parts price ranges plus labor hours times an assumed shop rate of $110 to $190 per hour. Actual prices vary by vehicle, region, and shop. Diagnosis fees are often extra.
| Repair | Parts | Labor | Estimate (low / high) |
|---|---|---|---|
| Spark plugs, full set | $20 to $120 | 0.5 to 2.5 h | $20 + 0.5 × $110 = $75 $120 + 2.5 × $190 = $595 |
| Vacuum hose or intake gasket | $10 to $120 | 0.5 to 2.5 h | $10 + 0.5 × $110 = $65 $120 + 2.5 × $190 = $595 |
| Ignition coil, one | $30 to $150 | 0.2 to 1.0 h | $30 + 0.2 × $110 = $52 $150 + 1.0 × $190 = $340 |
| Fuel pump | $120 to $600 | 1.5 to 3.5 h | $120 + 1.5 × $110 = $285 $600 + 3.5 × $190 = $1,265 |
Costs are generic for this code; parts and labor on some Honda models may run higher.
Watch a repair video
How to Fix a Random Engine Misfire in Your Car (Code P0300) (Scotty Kilmer). Third-party video, loads from YouTube (privacy-enhanced mode) only when you press play. Procedures vary by vehicle. Search YouTube for “P0300 Honda fix” videos.
Repair manuals
Step-by-step service manuals for Honda with torque specs and wiring diagrams:
Haynes manuals for Honda Chilton manuals
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Check Honda recalls
Enter your VIN at the NHTSA recall lookup before paying for repairs.
FAQ
Do Honda V6 engines burn oil?
Honda bulletins describe piston ring sticking on some engines that lets oil foul plugs. Check for warranty coverage.
Read the full P0300 guide or more Honda check engine notes.