Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
The car's computer noticed that cylinder number 12 in the engine isn't working properly. It's like one of the pistons isn't firing correctly, which can make the car run rough or feel shaky.
The engine control module (ECM) has detected that cylinder 12 is misfiring. This means the cylinder is not firing as it should, which can affect engine performance.
When the ECM detects that the combustion process in cylinder 12 is incomplete or irregular, it triggers the P0312 code. This can be due to various issues such as fuel delivery problems, ignition system faults, or mechanical engine issues.
• Rough engine idle
• Reduced engine performance
• Check engine light illuminated
• Increased emissions
• Poor fuel economy
• Faulty spark plug in cylinder 12
• Defective ignition coil for cylinder 12
• Fuel injector issue for cylinder 12
• Vacuum leak affecting cylinder 12
• Engine mechanical problem in cylinder 12
ECM: Engine Control Module
Misfire: A failure of the air/fuel mixture in the cylinder to ignite properly
Ignition Coil: A component that converts the battery's voltage to a higher voltage to ignite the fuel
• Use an OBD-II scanner to confirm the P0312 code.
• Inspect the spark plug and ignition coil for cylinder 12.
• Check the fuel injector for cylinder 12.
• Perform a compression test on cylinder 12.
• Inspect for vacuum leaks around cylinder 12.
• Replace the spark plug for cylinder 12.
• Replace or repair the ignition coil for cylinder 12.
• Clean or replace the fuel injector for cylinder 12.
• Repair any vacuum leaks found.
• Address any mechanical issues with cylinder 12.
• OBD-II scanner
• Spark plug socket
• Compression tester
$100 - $500
Moderate
• BMW 7 Series
• Mercedes-Benz S-Class
• Audi A8
• Regularly replace spark plugs and ignition components.
• Use high-quality fuel to prevent injector clogging.
• Perform routine engine maintenance checks.
Engine Performance
• Do not ignore the check engine light.
• Have the vehicle inspected by a professional mechanic.
• Avoid driving the vehicle aggressively until the issue is resolved.
Check with the vehicle manufacturer for warranty coverage on engine components.
Misfire codes like P0312 have been common as engines have become more complex, especially with multi-cylinder configurations.
Moderate – It is important to address this issue to prevent further engine damage and ensure optimal performance.
Driving with a misfire can lead to increased emissions and potential engine damage. It is advisable to have the issue diagnosed and repaired promptly.
• Engine at operating temperature
• Vehicle in idle or under load
Cylinder 12 is typically located at the rear of the engine on the passenger side in a V12 engine configuration.
Q: Can I drive with a P0312 code?
A: It's not recommended to drive with a misfire code as it can cause further damage to the engine and affect vehicle performance.
Q: What happens if I ignore a cylinder misfire?
A: Ignoring a misfire can lead to increased fuel consumption, higher emissions, and potential damage to the catalytic converter.
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Fitment Required · Vehicle-fitment part
Commonly relevant for misfire, ignition-efficiency, and some drivability-related repairs.
Misfire and ignition-related faults commonly involve spark plugs as part of the repair path.
Check the correct plug type, gap, and engine application for your vehicle.
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Fitment Required · Vehicle-fitment part
Relevant when the fault points toward ignition-coil performance or cylinder-specific ignition issues.
Some ignition faults involve coil performance or cylinder-specific coil problems.
Match the coil to your engine and confirm the failed component before ordering.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.