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 part that helps put fuel into one of the engine's cylinders. It's like if a toy car's battery isn't working right, so the car can't move properly.
The code P31A6 indicates an issue with the low side circuit of the hydrogen injector for cylinder 9, where the voltage is lower than expected.
The P31A6 code is triggered when the Engine Control Module (ECM) detects a low voltage condition in the low side circuit of the hydrogen injector for cylinder 9. This could be due to an electrical fault such as a short to ground, an open circuit, or a faulty injector.
• Check Engine Light is on
• Engine misfires or runs rough
• Reduced engine performance
• Faulty hydrogen injector
• Open or shorted wiring in the injector circuit
• Faulty ECM
Injector: A device that sprays fuel into the engine's cylinders.
ECM: Engine Control Module, the computer that controls engine functions.
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for cylinder 9 injector.
• Test the injector's resistance and operation.
• Repair or replace damaged wiring or connectors.
• Replace the faulty hydrogen injector.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$200 - $600
Moderate
• Toyota Mirai
• Honda Clarity Fuel Cell
• Hyundai Nexo
• Regular maintenance checks
• Ensure proper electrical connections
• Use quality fuel
Engine Performance
• Have the vehicle inspected by a professional.
• Avoid driving the vehicle if it runs rough.
• Regularly check for any warning lights.
Check with the vehicle manufacturer for warranty coverage on emissions-related components.
This code is relatively new and specific to hydrogen fuel cell vehicles, reflecting advancements in alternative fuel technology.
Moderate – It is advisable to address this issue soon to avoid potential engine performance problems.
Driving with a malfunctioning injector can lead to increased emissions and may not comply with emission regulations.
• Engine running
• Vehicle at operating temperature
The hydrogen injector for cylinder 9 is located on the engine, typically under the intake manifold.
Q: Can I drive with the P31A6 code?
A: It's not recommended to drive for long with this code, as it can lead to engine performance issues.
Q: What happens if I ignore this code?
A: Ignoring this code can cause engine misfires and reduced performance, potentially leading to more severe engine damage over time.
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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.