Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there's an issue with the injector that sprays fuel into the engine for cylinder number 7. It's like a hose that's supposed to spray water, but something is making it spray too much or too hard.
The engine control module (ECM) has detected that the high side circuit for the high-pressure fuel injector on cylinder 7 is experiencing a voltage higher than expected.
The P31CD code indicates that the ECM has detected an abnormally high voltage in the high side circuit of the high-pressure fuel injector for cylinder 7. This could be due to a short circuit, a faulty injector, or an issue with the wiring or connectors associated with the injector circuit.
• Check engine light is on
• Engine misfires
• Poor fuel economy
• Faulty fuel injector
• Short circuit in the injector wiring
• Faulty ECM
ECM: Engine Control Module
Injector: A component that sprays fuel into the engine's cylinders
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for cylinder 7's injector.
• Test the injector for proper operation.
• Replace the faulty injector.
• Repair or replace damaged wiring or connectors.
• Replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Injector tester
$200 - $600
Moderate
• Chevrolet Silverado
• GMC Sierra
• Cadillac Escalade
• Regular maintenance checks
• Ensure proper fuel quality
• Inspect wiring regularly
Engine Performance
• Do not ignore the check engine light.
• Have the vehicle inspected by a professional mechanic.
Check with the vehicle manufacturer for warranty coverage on injectors and ECM.
This code has been associated with injector circuit issues in vehicles with direct fuel injection systems.
Moderate – Should be addressed to prevent further engine performance issues.
Driving with a misfiring engine can cause damage to the catalytic converter and increase emissions.
• Engine at operating temperature
• Vehicle in a safe environment for testing
The injector for cylinder 7 is located on the engine block, typically on the driver's side for V8 engines.
Q: Can I drive with a P31CD code?
A: It's not recommended to drive with this code for an extended period, as it can lead to further engine damage.
Q: How do I know if my injector is bad?
A: Symptoms of a bad injector include engine misfires, rough idling, and poor fuel economy.
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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.