Parts
$8–120
P0305 — Cylinder 5 Misfire Detected
CAUTIONIs it safe to drive? Drive cautiously to a shop — continued misfiring damages the catalytic converter and can foul an oxygen sensor, but it's not immediately dangerous unless the misfire is severe and constant.
What P0305 means
The ECM counted enough combustion failures in cylinder 5 to set the code. That cylinder is either not getting spark, fuel, or compression, or combustion gases are escaping past a bad head gasket.
Most likely causes (in order)
- Spark plug (worn, fouled, or wrong gap — pull it first)
- Ignition coil or coil-on-plug boot for cylinder 5
- Fuel injector clogged or dead
- Intake manifold gasket leak on cylinder 5 port
- Low compression from worn rings or burned valve
Symptoms you might notice
- rough idle
- engine shaking
- hesitation on acceleration
- CEL flashing (stop immediately if flashing)
What to check first
Swap the cylinder 5 coil with a neighboring cylinder and clear codes — if the misfire follows the coil to the new cylinder, you found the culprit before buying anything.
Repair cost & difficulty
Labor
0.5–2 hr
Difficulty
DIY-friendly