P0311
Cylinder 11 Misfire DetectedP0311 is a generic OBD-II powertrain diagnostic trouble code: Cylinder 11 Misfire Detected. It is logged by the engine control unit when the misfire monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0311 means
P0311 is an OBD-II powertrain code indicating the engine control module has detected a misfire on cylinder number 11. Because only engines with eleven or more cylinders can physically have a cylinder 11, this code is in practice exclusive to V12 engines — most commonly found in high-end and performance vehicles from manufacturers such as BMW (N73, N74, S70), Mercedes-Benz (M120, M275, M279), Audi (W12), Ferrari, Lamborghini, Rolls-Royce, and Bentley. It will not appear on six, eight, or ten-cylinder engines.
The ECM detects the misfire by monitoring crankshaft rotational speed fluctuations. Each cylinder's power stroke is expected to provide a brief acceleration pulse; when cylinder 11 fails to contribute its pulse, the deceleration signature is logged and attributed to that cylinder's firing event. The MIL illuminates immediately, and a flashing MIL indicates a severe misfire that risks catalytic converter overheating — a particularly costly replacement on a 12-cylinder platform.
Causes mirror those of any cylinder-specific misfire: worn spark plug, failed ignition coil, faulty fuel injector, low compression from a burnt valve or head gasket failure, or a wiring fault on the coil driver circuit. On aging V12s, coil-on-plug units degrade with heat cycling and are the most statistically common culprit. Given the accessibility challenges of cylinder 11 in densely packaged V12 engine bays, a swap test with an adjacent cylinder's coil and plug is the most efficient first diagnostic step.
Common causes
Most-frequently reported root causes when P0311 is logged.
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1
Worn or fouled spark plug on cylinder 11 causing incomplete combustion.
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2
Failed ignition coil-on-plug unit on cylinder 11 producing no or weak spark.
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3
Clogged or electrically failed fuel injector on cylinder 11 starving that cylinder of fuel.
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4
Low cylinder compression from a burnt or bent exhaust valve, failed head gasket, or worn piston rings on cylinder 11.
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5
Damaged wiring or corroded connector in the ignition coil driver circuit for cylinder 11.
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6
Vacuum leak at the intake runner or manifold gasket serving cylinder 11 causing a lean condition.
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7
Faulty camshaft or crankshaft position sensor producing incorrect misfire cylinder attribution.
Symptoms drivers notice
How to diagnose P0311
A typical diagnostic flow when this code is present.
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1
Connect a scan tool capable of reading V12 freeze frame data; confirm P0311 and check for companion codes on adjacent cylinders or ignition/fuel systems.
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2
Monitor live per-cylinder misfire counters to confirm cylinder 11 is the primary source and not a secondary reflection of a multi-cylinder fault.
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3
Perform a coil-on-plug and spark plug swap between cylinder 11 and a known-good cylinder; re-scan to determine whether the misfire count migrates.
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4
Test the cylinder 11 fuel injector for correct resistance and audible click using a stethoscope; compare with adjacent injectors.
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5
Perform a compression and leak-down test on cylinder 11 to rule out mechanical failure such as a valve or head gasket issue.
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6
Inspect the cylinder 11 wiring harness and connector for chafing, heat damage, or corrosion given the typically congested V12 engine bay.
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7
If ignition and fuel components pass, measure ECM coil driver output voltage with an oscilloscope before replacing the module.
Related powertrain codes
Frequently asked questions
Can a 6-cylinder or 8-cylinder engine produce P0311?
No. P0311 specifically designates cylinder 11, which only exists on an engine with at least 11 cylinders. In practice this means V12 engines. If P0311 appears on a non-V12 vehicle, suspect a scan tool error or module fault.
Is a misfire on a V12 less serious than on a smaller engine?
The mechanical risk is similar — raw fuel entering the catalytic converter can destroy it regardless of cylinder count. However, a V12 running on 11 cylinders may feel smoother than a 4-cylinder on 3, which can delay owner awareness. The flashing MIL threshold should still be taken seriously.
How hard is it to access cylinder 11 on a V12 for a spark plug change?
Accessibility varies widely by model. On most V12s (e.g., BMW N73, Mercedes M275) the rear cylinders of each bank are deep in the engine bay under intake plenums or heat shields. Some require partial disassembly of the intake manifold, making ignition service significantly more labour-intensive than on a 4-cylinder.
Can a failed ignition coil on cylinder 11 damage other components?
Yes. If the cylinder 11 coil fails open, unburned fuel is expelled into the exhaust. Sustained misfire events can overheat and melt catalytic converter substrate. Additionally, fuel washing cylinder 11's bore can dilute oil and accelerate ring and bore wear.
Disabling P0311 in software
RaceTune can permanently disable P0311 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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