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 has detected a problem with the fuel injector for cylinder 12. It's like when a water hose is turned on too high and sprays too much water.
This code indicates that the electrical circuit for the high-pressure fuel injector on cylinder 12 is experiencing a higher than normal voltage.
The P31D7 code is triggered when the Engine Control Module (ECM) detects a high voltage condition in the high side circuit of the high-pressure fuel injector for cylinder 12. This could be due to a short to voltage or an open circuit.
• Check Engine Light is on
• Engine misfire
• Poor fuel economy
• Faulty high-pressure fuel injector
• Wiring issues such as short to voltage
• Faulty ECM
ECM: Engine Control Module
OBD-II: On-Board Diagnostics II
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for cylinder 12 injector.
• Test the injector for proper resistance and operation.
• Replace the faulty injector.
• Repair or replace damaged wiring.
• Replace or reprogram the ECM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$200 - $600
Moderate
• High-performance vehicles
• Luxury cars with V12 engines
• Certain diesel trucks
• Regular maintenance of the fuel system
• Timely replacement of fuel filters
• Periodic inspection of electrical connections
Engine Performance
• Avoid driving the vehicle if the engine is misfiring.
• Consult a professional mechanic for accurate diagnosis.
• Keep up with regular vehicle maintenance.
Check with the vehicle manufacturer for warranty coverage on fuel injectors.
This code is more common in high-performance engines due to the complexity of their fuel systems.
High – Ignoring this issue can lead to engine damage.
Driving with a misfiring engine can be unsafe and may cause further damage.
• Engine running
• Vehicle at operating temperature
The high-pressure fuel injector for cylinder 12 is located on the engine, typically near the intake manifold.
Q: Can I drive with a P31D7 code?
A: It's not recommended to drive with this code as it can lead to engine damage.
Q: How do I know if my injector is faulty?
A: Symptoms include engine misfires, poor fuel economy, and a check engine light.
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A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
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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.