P0302 — Cylinder 2 misfire detected

P0302 means the engine controller detected combustion misfires in cylinder 2. Locate cylinder numbering from the engine documentation, not by assumption. The code identifies a combustion event, not a proven defective coil: ignition (where spark ignition exists), injection, mixture or compression can be responsible. Severe misfires may damage the catalytic converter.

Affected system: Cylinder combustion

Symptoms

• Rough idle, hesitation or reduced power.
• Engine warning lamp lit or flashing; flashing during active misfires requires stopping safely.
• Potential increased consumption, unburned-fuel smell or hard starts on some engines.

Possible causes

• Faulty plug/coil or oil/water in the plug well on spark-ignition engines only.
• Cylinder 2 injector delivery or control fault, or a fuel-supply problem.
• Poor cylinder 2 compression or another mechanical sealing/valve problem.
• Local intake leak or mixture/timing concern where related codes support that direction.

What to check

• 1. Save DTCs, freeze-frame and per-cylinder misfire counters if available; note load, temperature and whether other cylinders also misfire.
• 2. If the MIL flashes or the engine shakes severely, stop safely and avoid further driving: unburned fuel may overheat the catalyst. Do not road-test severe active misfires.
• 3. Identify cylinder 2 from the exact engine layout. Inspect connectors, wiring and oil or water contamination near the relevant ignition/injection parts.
• 4. On spark-ignition engines inspect cylinder 2 plug, insulation and coil with ignition off, comparing part condition and specifications with OEM data. Never touch live high-voltage components.
• 5. Where the ignition design allows it, a workshop may swap a compatible coil to another cylinder and see whether the misfire follows it. Only then is the coil strongly implicated; do not use this on shared-coil or incompatible designs.
• 6. If ignition is sound or the engine has no spark plugs, test injection using permitted live data and actuator procedures. Electrical and hydraulic injector tests, especially high-pressure systems, require trained personnel.
• 7. If cylinder 2 still misfires, perform a vehicle-specific compression test and if indicated a leak-down test. Low compression points toward mechanical causes, not an automatic plug replacement.
• 8. Repair only the demonstrated fault, clear DTCs and review misfire counters under safe original conditions without provoking severe misfires. Do not replace all cylinder components solely because P0302 was logged.

Step-by-step repair guide

• Misfires P0300–P0304: how to test ignition coils and spark plugs step by step

Also written as: P0302-00, P030200, PO302 (some scan tools add the fault-type byte, e.g. -00).