OBD-II Code P0311 — What It Means & How to Fix It

What Does This Error Mean?

P0311 means the engine computer detected a misfire in cylinder 11. The air/fuel mixture in cylinder 11 failed to ignite correctly — or not at all. This only appears on engines with 11 or more cylinders, such as some V12 configurations. You'll likely feel rough running, vibration, and reduced power. Don't delay repairs — misfires cause catalytic converter damage over time.

Affected Models

All vehicles 1996+ with 11+ cylinders
Common in BMW 760i V12
Common in Mercedes-Benz S600 V12
Common in Audi A8 W12
Common in Lamborghini V12 models

Common Causes

Worn or fouled spark plug in cylinder 11 that can no longer create a reliable spark
Failed ignition coil for cylinder 11 not delivering adequate voltage to the plug
Faulty or clogged fuel injector causing insufficient fuel delivery to cylinder 11
Vacuum leak near the cylinder 11 intake causing a lean condition in that cylinder
Low compression in cylinder 11 from worn rings, damaged valves, or a failing head gasket

How to Fix It

Use an OBD-II scanner to pull all codes. Note any companion codes for cylinder 11 — injector circuit codes (P0296, P0297) or coil codes can help narrow down the cause before you start replacing parts.

Free loaner scanners are available at many auto parts stores.
Access and remove the spark plug for cylinder 11. On a V12, this can be challenging depending on the engine layout. Inspect the plug for fouling, cracks, or worn electrode. Replace with the manufacturer-specified plug type.

Even if only one cylinder is misfiring, consider replacing all plugs if they are near the end of their service life.
On coil-on-plug systems, swap the coil from cylinder 11 with a coil from a known good cylinder. Clear the codes and drive for a short period. If the misfire code moves to the new cylinder, the coil is the problem.

This swap test is free and eliminates guesswork before buying a new coil.
Inspect the fuel injector connector for cylinder 11. Look for corrosion or damage. If the connector is clean, listen for injector clicking with the engine running using a mechanic's stethoscope. No click means the injector isn't firing.

A fuel injector that clicks but still causes a misfire may have a weak spray pattern — consider professional cleaning.
If all ignition and fuel components test correctly, schedule a compression test at a shop. Low compression in cylinder 11 compared to other cylinders points to a mechanical issue requiring internal engine repair.

A wet compression test (with oil added) can help distinguish between ring wear and valve problems.

When to Call a Professional

V12 engines are complex and cylinder access can be difficult. If basic ignition and injector checks don't resolve the misfire, have a professional mechanic perform a compression and leak-down test. Internal engine problems in a V12 are labor-intensive and expensive to repair. Expect $150-$400 for full spark plug replacement on a V12, and $500-$3,000+ for internal repairs.

Frequently Asked Questions

What engines have a cylinder 11?

Only engines with 11 or more cylinders have a cylinder 11. This means V12 and W12 engines found in luxury and exotic vehicles. Examples include the BMW 7-series V12, Mercedes-Benz S600 V12, Audi A8 W12, Lamborghini Murciélago V12, and Ferrari V12 models. If your vehicle has fewer than 11 cylinders and shows P0311, verify the code was read correctly.

Can I drive with P0311?

You can drive short distances, but it's not advisable. A V12 running with one misfiring cylinder loses 8% of its power and puts extra stress on the other 11 cylinders. Unburned fuel entering the exhaust also risks damaging the catalytic converter. If the check engine light is flashing, stop driving immediately.

Why would only one cylinder misfire on a V12?

Single-cylinder misfires almost always point to a component specific to that cylinder — the spark plug, coil, or injector. If a system-wide issue like low fuel pressure or a vacuum leak were the cause, multiple cylinders would typically misfire. Start your diagnosis with the plug and coil, since they are the cheapest and most likely culprits.