P0305

Cylinder 5 Misfire Detected

OBD-II diagnostic trouble code P0305indicates 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

• Flashing or steady Check Engine Light
• Engine running rough with noticeable vibration
• Loss of power and hesitation
• Increased fuel consumption
• Risk of catalytic converter damage if driven long distances while misfiring

Possible Causes

• Worn or fouled spark plug on cylinder 5
• Faulty ignition coil (or spark plug wire on older engines) for cylinder 5
• Clogged or leaking fuel injector on cylinder 5
• Low compression in cylinder 5 — burnt valve, worn rings, head gasket failure
• Intake manifold gasket leak at cylinder 5 runner
• Carbon buildup on intake valves (direct injection engines)

Common Fixes

• Replace cylinder 5 spark plug ($10-30 DIY, $80-150 shop)
• Test and replace coil/wire for cylinder 5 ($50-200)
• Clean or replace cylinder 5 fuel injector ($80-400)
• Compression test and engine diagnosis ($100-200 test, $1500-4000 if major repair needed)
• Intake valve carbon cleaning (DI engines, $400-800)

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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