P0305 Cylinder 5 Misfire Detected

P0305 indicates a detected misfire on cylinder 5. The code identifies the cylinder but not the cause, which can be ignition, fuel, compression, air, or control related.

Code details

Generic OBD-II · P0

System: Ignition / Misfire
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not assume the coil is bad just because cylinder 5 is named; prove whether the fault follows spark, fuel, compression, or wiring.

Symptoms of P0305

Rough idle or a distinct shake, often worse at low RPM.
A stumble or dead spot traced to cylinder 5.
A flashing check-engine light when the misfire is active.
Slight power loss and worse fuel economy.

Common causes of P0305

A worn spark plug or failed ignition coil on cylinder 5.
A clogged, leaking, or dead injector on cylinder 5.
A vacuum leak or low compression local to that cylinder.
Carbon-tracked plug boot or damaged coil wiring.

Useful checks before replacing parts

Compare cylinder 5 misfire counters with other cylinders under idle, cruise, and load.
Check ignition parts, injector operation, compression, leakdown, vacuum leaks near that runner, and connector condition.
Use freeze-frame data to decide whether the misfire is cold-start, idle-only, load-related, or constant.

Related OBD-II codes

These nearby ignition / misfire entries can help compare wording and pin down the fault area.