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 the computer in the car thinks there's a problem with the injector for cylinder number 9. It's like a tiny hose that sprays fuel into the engine, and the computer thinks it's getting too much power.
The P31D1 code indicates an issue with the electrical circuit that controls the high-pressure fuel injector for cylinder 9. The circuit is receiving more voltage than expected.
The P31D1 code is triggered when the Engine Control Module (ECM) detects a high voltage condition in the high side circuit of the high-pressure injector for cylinder 9. This could be due to a short circuit, a faulty injector, or an issue with the wiring or connectors.
• Engine misfire
• Poor fuel economy
• Check Engine Light illuminated
• Faulty fuel injector
• Short circuit in the wiring
• Faulty ECM
ECM: Engine Control Module
Injector: A device that sprays fuel into the engine
• Inspect the wiring and connectors for damage.
• Test the fuel injector for proper operation.
• Check the ECM for faults.
• Replace or repair damaged wiring.
• Replace the faulty fuel injector.
• Reprogram or replace the ECM if necessary.
• Multimeter
• OBD-II scanner
• Fuel injector tester
$200 - $600
Moderate
• Chevrolet Silverado
• GMC Sierra
• Cadillac Escalade
• Regular maintenance checks
• Ensure proper fuel quality
• Inspect wiring periodically
Engine Performance
• Avoid driving the vehicle until repaired.
• Consult a professional mechanic.
Check with your vehicle manufacturer for specific warranty coverage related to the fuel injector system.
This code has been associated with high-performance engines where precise fuel delivery is critical.
High – This issue can lead to engine misfires and reduced performance.
Operating a vehicle with this issue can lead to increased emissions and potential engine damage.
• Engine running
• Under load conditions
The fuel injector for cylinder 9 is located on the engine block, typically near the intake manifold.
Q: Can I drive with a P31D1 code?
A: It's not recommended as it can cause further engine damage.
Q: How can I reset the P31D1 code?
A: Fix the underlying issue first, then use an OBD-II scanner to clear the code.
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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.