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 is a problem with the part of the car that helps spray fuel into the engine for cylinder number 3. It's like a hose not working properly to water a plant.
The P31C4 code indicates that the electrical circuit controlling the high-pressure fuel injector for cylinder 3 is not working correctly. Specifically, the voltage is lower than expected.
The P31C4 code is triggered when the Engine Control Module (ECM) detects a low voltage condition in the high side circuit of the high-pressure fuel injector for cylinder 3. This could be due to wiring issues, a faulty injector, or problems with the ECM itself.
• Engine misfire
• Reduced engine performance
• Check Engine Light illuminated
• Faulty high-pressure injector for cylinder 3
• Wiring issues such as short circuits or open circuits
• Faulty Engine Control Module (ECM)
ECM: Engine Control Module, the computer that controls engine functions.
Injector: A device that sprays fuel into the engine's cylinders.
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for cylinder 3 injector.
• Test the injector for proper operation.
• Replace or repair faulty wiring or connectors.
• Replace the high-pressure injector for cylinder 3.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Fuel injector tester
$200 - $600
Moderate
• BMW 3 Series
• Audi A4
• Volkswagen Passat
• Regular maintenance and inspection of fuel system components
• Ensure proper fuel quality
• Check wiring and connectors periodically
Engine Performance
• Do not ignore the Check Engine Light.
• Seek professional diagnosis if unsure.
• Avoid driving long distances until the issue is resolved.
Check with your vehicle manufacturer for specific warranty coverage on fuel injectors.
This code has been associated with vehicles using direct fuel injection systems, which are more sensitive to electrical issues.
Moderate – It should be addressed soon to prevent further engine performance issues.
Driving with a malfunctioning injector can lead to increased emissions and potential engine damage.
• Engine running
• Warm engine temperature
The high-pressure fuel injector for cylinder 3 is located on the engine, typically near the intake manifold for cylinder 3.
Q: Can I drive my car with a P31C4 code?
A: It's not recommended to drive for long distances, as it may cause engine performance issues.
Q: How do I clear a P31C4 code?
A: After repairing the issue, 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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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.