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 there is a problem with the fuel injector in cylinder 2 of the engine. It's like the injector isn't getting enough power to work properly.
The engine control module (ECM) has detected a low voltage or open circuit condition in the high side of the injector circuit for cylinder 2.
The P31C2 code indicates that the ECM has detected an issue with the high side circuit of the fuel injector for cylinder 2. This could be due to a low voltage condition or an open circuit, which prevents the injector from operating correctly. The high side circuit is responsible for providing the necessary voltage to the injector to open and allow fuel to be sprayed into the cylinder.
• Engine misfire
• Poor fuel economy
• Rough idle
• Faulty injector
• Damaged wiring or connectors
• Faulty ECM
ECM: Engine Control Module
Injector: A device that sprays fuel into the engine's cylinders
• Inspect the wiring and connectors for damage.
• Test the injector for proper operation.
• Check the ECM for faults.
• Repair or replace damaged wiring/connectors.
• Replace the faulty injector.
• Replace or reprogram the ECM if necessary.
• Multimeter
• OBD-II scanner
• Injector tester
$200 - $600
Moderate
• BMW 3 Series
• Mercedes-Benz C-Class
• Audi A4
• Regular maintenance checks
• Timely replacement of fuel filters
• Use quality fuel
Engine Performance
• Avoid driving with this code active as it may lead to further engine damage.
• Seek professional diagnosis and repair.
Check with your vehicle manufacturer for warranty coverage on injectors and related components.
This code has been associated with injector circuit issues in direct injection engines, particularly in European vehicles.
High – This issue can lead to engine damage if not addressed promptly.
Driving with a misfiring engine can be dangerous and may not comply with emissions regulations.
• Engine running
• ECM active
The injector for cylinder 2 is located on the engine, typically on the intake manifold or cylinder head.
Q: Can I drive with a P31C2 code?
A: It's not recommended as it can cause engine damage and poor performance.
Q: How do I know if my injector is faulty?
A: Symptoms include misfires, rough idle, and poor fuel economy. A professional diagnosis is recommended.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
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.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.
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.