OBD codes / P0311
P0311
SeriousCylinder 11 Misfire Detected
Treat P0311 with urgency. A steady light with mild symptoms is drivable short-term; a FLASHING light means raw fuel is reaching the catalytic converter — ease off immediately and get the car seen. On a V12 the misfire may feel trivial, but the catalysts it threatens are anything but cheap.
What this code means
P0311 means cylinder 11 is misfiring — failing to burn its air-fuel charge reliably. A cylinder 11 only exists on twelve-cylinder engines (and rare configurations beyond ten), so in practice this is a V12 code found on high-end luxury and performance cars. The diagnostic logic is the same as any single-cylinder misfire: the leading causes are that cylinder's spark plug or ignition coil, verified by swapping the part to a neighboring cylinder and watching whether the misfire follows. A weak or clogged fuel injector and low compression are the less common possibilities. V12s mask single-cylinder misfires well — the engine can feel nearly smooth — but the unburned fuel still overheats the catalytic converter on that bank, and V12 catalyst hardware is among the most expensive to replace. Cylinder numbering varies by manufacturer, so confirm which cylinder is 11 before pulling parts.
Symptoms you might notice
- Slight roughness or vibration, often subtle on a V12
- Reduced power or hesitation under load
- Flashing check-engine light during an active misfire
- Reduced fuel economy
- Fuel smell from the exhaust in severe cases
What it costs to fix
Varies by vehicle — get it diagnosed.
The repair cost for this code depends too much on your exact vehicle and the underlying cause to quote a meaningful range. Confirm the cause first so you only pay for the fix you actually need.
Diagnose P0311 for my vehicle →Frequently asked
What vehicles get P0311?
Only engines with eleven or more cylinders — effectively V12s in luxury and performance cars. If a smaller engine shows this code, suspect a scan-tool misread or a spurious stored code and re-scan before doing anything else.
The engine feels fine — do I still need to fix it?
Yes. A V12 hides one dead cylinder well, but the misfiring cylinder is still pushing unburned fuel into the exhaust, which overheats the catalytic converter over time. Catching it while it's a plug or coil is far cheaper than adding a catalyst to the bill.
Is it the coil, the plug, or the injector?
Statistically the plug or coil. Swap the suspect coil (or plug) with a neighboring cylinder and clear the code — if the misfire follows the part, you've found it. If it stays on cylinder 11, test the injector and then compression.
Can I drive with P0311?
Short, gentle trips with a steady light are usually acceptable while you arrange the repair. A flashing light means an active, catalyst-damaging misfire — reduce load immediately and have it diagnosed or towed.
Seeing P0311 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0311 for my vehicleRelated trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0311 from your phone — see our honest guide to the best OBD2 Bluetooth adapters.
Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.