Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that there's a problem with the electrical circuit that controls the fuel injector for cylinder 12 in your car's engine. It's like a light switch that isn't working right, so the fuel injector can't do its job properly.
The P31D6 code indicates an issue with the electrical circuit responsible for the high-pressure fuel injector in cylinder 12. The circuit is reading as low, meaning it might not be providing enough voltage or current to operate the injector correctly.
The P31D6 code is triggered when the Engine Control Module (ECM) detects a low voltage condition in the high side circuit of the high-pressure injector for cylinder 12. This could be due to a wiring issue, a faulty injector, or a problem with the ECM itself.
• Engine misfire
• Reduced engine performance
• Check Engine Light on
• Faulty high-pressure injector
• Damaged wiring or connectors
• Faulty ECM
ECM: Engine Control Module, the computer that controls engine functions.
Injector: A device that sprays fuel into the engine's cylinders.
• Inspect wiring and connectors for damage
• Test the injector for proper operation
• Check ECM for faults
• Repair or replace damaged wiring
• Replace faulty injector
• Reprogram or replace ECM if necessary
• Multimeter
• OBD-II scanner
• Injector tester
$200 - $1000 depending on the exact issue
Difficult
• Vehicle 1
• Vehicle 2
• Vehicle 3
• Regular maintenance checks
• Ensure proper fuel quality
• Inspect electrical connections periodically
Engine Performance
• Have a professional diagnose the issue
• Avoid driving the vehicle until fixed to prevent further damage
Check with the vehicle manufacturer for warranty coverage on injectors and ECM issues.
This code is relatively uncommon and typically associated with high-performance or specialized engines with multiple cylinders.
High – This issue can lead to engine damage if not addressed promptly.
Driving with this code active may not comply with emissions regulations and can be unsafe.
• Engine at operating temperature
• Vehicle in a safe location
The injector is located on the engine, specifically at cylinder 12, which may require engine covers to be removed for access.
Q: Can I drive with a P31D6 code?
A: It's not recommended to drive with this code active as it can lead to engine damage.
Q: What causes a high side circuit to be low?
A: Possible causes include damaged wiring, a faulty injector, or issues with the ECM.
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Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
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Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
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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.