Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This means there's a problem with the part of the engine that helps inject fuel into cylinder 7. It's like a wire is touching something it shouldn't, causing a short circuit.
The engine control module (ECM) has detected a short circuit in the high side of the injector circuit for cylinder 7, where the injector is electrically connected to the coil.
The P31B7 code indicates that the ECM has identified a short circuit condition in the high side of the injector circuit for cylinder 7. This short is specifically between the injector's high side and the ignition coil, which can disrupt the proper operation of the injector and potentially affect the performance of the engine.
• Engine misfire
• Poor fuel economy
• Check Engine Light is on
• Damaged wiring harness
• Faulty injector
• Short circuit in the ignition coil
ECM: Engine Control Module
Injector: A device that sprays fuel into the engine's cylinders
• Inspect the wiring and connectors for damage or corrosion.
• Test the injector for proper operation.
• Check the ignition coil for shorts or faults.
• Repair or replace damaged wiring.
• Replace the faulty injector.
• Replace the ignition coil if necessary.
• Multimeter
• OBD-II scanner
• Wrench set
$150 - $500
Moderate
• Vehicle 1
• Vehicle 2
• Vehicle 3
• Regularly inspect wiring for damage.
• Ensure proper maintenance of injectors.
• Avoid harsh driving conditions that could damage engine components.
Engine Performance
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional if unsure.
Check with your vehicle manufacturer for specific warranty coverage related to engine components.
This code has been associated with vehicles that have experienced injector circuit issues, particularly in high-mileage engines.
Moderate – It should be addressed soon to avoid further engine performance issues.
Driving with a misfiring engine can lead to increased emissions and potential safety hazards.
• Engine running
• Warm operating temperature
The injector for cylinder 7 is located on the engine block, typically on the side or top, depending on the engine configuration.
Q: Can I drive with a P31B7 code?
A: It's not recommended to drive for extended periods with this code as it can lead to further engine damage.
Q: How do I reset the Check Engine Light after repair?
A: Use an OBD-II scanner to clear the code after the repair is completed.
High-End · Full-system diagnostics
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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.