P0305
Cylinder 5 Misfire Detected
Ignition / misfire
Generic OBD-II
High
What it means
P0305 means cylinder 5 is misfiring — its fuel isn't burning properly, so the engine runs rough and loses power. Because a misfiring cylinder sends unburned fuel into the exhaust, sustained misfires can overheat and destroy the catalytic converter, making this a code to fix quickly.
High
Can I keep driving? Drive as little as possible — an active misfire (especially a flashing light) can quickly damage the catalytic converter.
Common symptoms
What you'll notice
- Check-engine light on (may flash during an active misfire)
- Rough idle, shaking, or stalling
- Hesitation and loss of power on acceleration
- Increased fuel consumption
Common causes
Most likely first
- Worn spark plug on cylinder 5Likely
- Failing ignition coil on cylinder 5Common
- Clogged or leaking fuel injector on cylinder 5Common
- Vacuum leak near cylinder 5Less often
- Low compression on cylinder 5 (valves, rings, head gasket)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data, then inspect the cylinder 5 spark plug and coil first — the most common cause.
- Swap the coil (and plug) with a neighbouring cylinder; if the misfire follows, replace that part.
- Check the cylinder 5 injector and look for vacuum leaks nearby.
- If it persists, run a compression test on cylinder 5. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0305?+
No — especially with a flashing light. A single-cylinder misfire dumps raw fuel into the exhaust and can ruin the catalytic converter.
Can I just clear P0305?+
It comes back within a few drive cycles until the misfire on cylinder 5 is repaired.
Related codes
Often seen with P0305
Read & clear P0305 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX