P0311 critical

Cylinder 11 Misfire Detected

The P0311 code means the vehicle's onboard diagnostic system has detected: Cylinder 11 Misfire Detected. This is a critical severity code.

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Keep driving?: Short distances only
DIY difficulty: moderate
Estimated cost: $100 - $800 (parts and labor)

Fix Your Misfire

Magnetic Spark Plug Socket Set with Gap Tool

The #1 fix for misfire codes. 15-piece set with 14mm, 16mm, 18mm magnetic sockets, T-handle extension, and spark plug gapper.

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Diagnose It First

ANCEL AD310 OBD-II Scanner

Read and clear misfire codes. Shows which cylinder is misfiring so you know exactly what to replace.

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Common Symptoms

Engine misfire on cylinder 11
Rough idle and vibration
Check Engine Light flashing
Reduced power output
Exhaust has fuel smell

Probable Causes (Ranked by Likelihood)

Faulty spark plug or ignition coil on cylinder 11 Very High
Fuel injector failure on cylinder 11 High
Low compression in cylinder 11 Moderate
Vacuum leak near cylinder 11 intake Moderate
Timing chain or valve train issue Low

Step-by-Step Diagnostic Procedure

Inspect and replace spark plug on cylinder 11 -- check for fouling, damage, or incorrect gap
Swap ignition coil from cylinder 11 with a known-good cylinder and retest
Test fuel injector operation using a noid light and resistance measurement
Perform a compression test on cylinder 11
Check for vacuum leaks around cylinder 11 intake runner

Frequently Asked Questions

Can I drive with code P0311?

You can drive short distances if the light is steady. A flashing Check Engine Light means catalytic converter damage is imminent -- stop driving and have the vehicle towed.

What vehicles have a cylinder 11?

Only V12 engines have a cylinder 11. These are typically found in luxury and high-performance vehicles from Ferrari, Lamborghini, Mercedes-Benz, BMW, and Aston Martin.

Are V12 misfires expensive to fix?

The repair cost for the misfire itself (spark plug, coil, injector) is similar to other engines. However, labor costs on V12 engines are higher due to the complexity and tight packaging of the engine bay.