All codes
P0305Engine Problems
Cylinder 5 Misfire Detected - Causes & Fixes
Learn what P0305 means, why cylinder 5 is misfiring, and how to diagnose and fix it with a clear step-by-step approach.
What you may notice
Symptoms
- 01Check engine light on or flashing
- 02Rough idle and engine vibration
- 03Power loss on acceleration
- 04Poor fuel economy
- 05Occasional stumble or hesitation
Where to look first
Common causes
- 01Worn or fouled spark plug in cylinder 5
- 02Faulty ignition coil on cylinder 5
- 03Clogged or leaking fuel injector
- 04Vacuum leak near cylinder 5
- 05Low compression in cylinder 5
Step by step
What to check and repair
- 01Replace the cylinder 5 spark plug
- 02Swap the coil to test, replace if faulty
- 03Test and clean or replace the fuel injector
- 04Check for vacuum leaks and repair
- 05Perform a compression test if other fixes fail
What Does P0305 Mean?
The P0305 code indicates the engine control module (ECM) has detected a misfire in cylinder 5. The mixture in that cylinder is failing to ignite reliably, which reduces power and can damage the catalytic converter if ignored.
Quick Isolation Trick
Swap the ignition coil from cylinder 5 with a neighboring cylinder. If the misfire code follows the coil, the coil is the problem; if it stays on cylinder 5, look at the plug, injector, or compression.
How AI4Car Helps
AI4Car shows misfire counts per cylinder in real time, so you can confirm cylinder 5 is the offender and check whether a repair actually cleared it.