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 part of the car that sprays fuel into the engine. It might be getting too much power, like a light bulb that's too bright.
The code indicates that the electrical circuit controlling the high-pressure fuel injector for cylinder 1 is receiving a higher voltage than expected.
P31C5 is set when the Engine Control Module (ECM) detects a high voltage condition in the high side circuit of the high-pressure fuel injector for cylinder 1. This could be due to a wiring issue, a faulty injector, or a problem with the ECM itself.
• Engine misfire
• Poor fuel economy
• Check Engine Light on
• Faulty fuel injector
• Wiring harness issues
• Malfunctioning ECM
ECM: Engine Control Module
Injector: A device that sprays fuel into the engine
• Perform a visual inspection of the wiring and connectors.
• Use a multimeter to check the voltage and resistance in the injector circuit.
• Test the injector for proper operation.
• Repair or replace damaged wiring or connectors.
• Replace the faulty injector.
• Reprogram or replace the ECM if necessary.
• Multimeter
• OBD-II scanner
• Basic hand tools
$200 - $800
Moderate
• Vehicle 1
• Vehicle 2
• Vehicle 3
• Regular maintenance checks
• Ensure proper fuel quality
• Inspect wiring and connectors periodically
Engine Performance
• Avoid driving with a flashing Check Engine Light.
• Seek professional diagnosis if unsure.
• Regularly maintain your vehicle to prevent such issues.
Check with the vehicle manufacturer for specific warranty coverage related to fuel injectors.
This code has been associated with high-pressure fuel systems in modern vehicles and can lead to significant engine performance issues if not addressed.
High – This issue can lead to engine damage if not addressed promptly.
Driving with a malfunctioning injector can lead to increased emissions and may not comply with local emissions regulations.
• Engine running
• Vehicle at operating temperature
The high-pressure fuel injector is located on the engine, typically near the intake manifold of cylinder 1.
Q: Can I drive with a P31C5 code?
A: It's not recommended as it can cause further engine damage.
Q: How can I prevent this code from occurring?
A: Regular maintenance and using quality fuel can help prevent this issue.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
Network faults often require full-system access instead of a generic code reader alone.
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Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
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Universal · Wire connectors and repair kit
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.