P0311
Cylinder 11 Misfire Detected
Ignition / misfire
Generic OBD-II
High
What it means
P0311 means the engine computer has detected a misfire on cylinder 11 — fuel isn't burning properly there, so the engine runs rough and loses power. This code appears on engines with 12 or more cylinders. Sustained misfires can overheat and damage the catalytic converter.
High
Can I keep driving? Drive as little as possible — an active misfire, especially with a flashing check-engine 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
- Reduced power and hesitation on acceleration
- Increased fuel consumption
Common causes
Most likely first
- Worn spark plug or failing ignition coil on cylinder 11Likely
- Clogged or leaking fuel injector on cylinder 11Common
- Vacuum leak near cylinder 11 or low fuel pressureCommon
- Low compression on cylinder 11 (valves, rings, head gasket)Less often
- Faulty engine control module (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data, then inspect and replace the cylinder 11 spark plug and coil — the most common cause.
- Swap the coil/injector with a neighbouring cylinder and see if the misfire follows to confirm the failed part.
- Check fuel delivery to cylinder 11 and test for nearby vacuum leaks.
- If it persists, run a compression test on cylinder 11 for mechanical causes. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0311?+
No — a sustained misfire can overheat and destroy the catalytic converter, especially if the light is flashing.
Can I just clear P0311?+
You can, but it returns within a few drive cycles until the cause on cylinder 11 is repaired.
Related codes
Often seen with P0311
Read & clear P0311 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