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 a problem with the injector in cylinder 8 of your car's engine. It's like a wire is touching something it shouldn't, causing a short circuit.
The P31B8 code indicates that the high side of the injector circuit for cylinder 8 is shorted to the coil. This can cause improper fuel injection and engine performance issues.
The P31B8 code is triggered when the Engine Control Module (ECM) detects a short circuit between the high side of the fuel injector for cylinder 8 and the ignition coil. This short can disrupt the proper operation of the injector, leading to fuel delivery issues.
• Check engine light is on
• Engine misfires
• Poor fuel economy
• Damaged or frayed wiring in the injector circuit
• Faulty injector for cylinder 8
• Malfunctioning ignition coil
Injector: A device that delivers fuel into the engine's combustion chamber.
Coil: An ignition coil transforms the battery's voltage to a higher voltage to ignite the fuel.
• Check for any visible wiring damage around cylinder 8 injector and coil.
• Use a multimeter to test the injector circuit for shorts.
• Inspect the ignition coil for cylinder 8.
• Repair or replace damaged wiring.
• Replace the faulty injector.
• Replace the malfunctioning ignition coil.
• Multimeter
• OBD-II scanner
• Basic hand tools
$150 - $500
Moderate
• Ford F-150
• Chevrolet Silverado
• Dodge Ram 1500
• Regularly inspect engine wiring for wear and tear.
• Perform routine maintenance checks.
• Ensure injectors and coils are clean and functioning properly.
Engine Performance
• Avoid driving the vehicle until the issue is fixed to prevent further damage.
• Consult a professional mechanic if unsure about repairs.
Check with your vehicle manufacturer for potential coverage under powertrain warranty.
This code is relatively uncommon and usually associated with specific wiring or component failures.
High – This issue can lead to engine performance problems and should be addressed promptly.
Driving with this code can lead to increased emissions and potential engine damage.
• Engine at operating temperature
• Vehicle in a safe, stationary position
The injector for cylinder 8 is located on the engine block, typically near the rear of the engine on the passenger side.
Q: Can I drive my car with a P31B8 code?
A: It's not recommended as it can cause further damage to your engine.
Q: How can I prevent this issue?
A: Regular maintenance and inspections of the engine wiring and components can help prevent such issues.
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Universal · Digital multimeter
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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.