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 for cylinder 12 in the engine. It's like one of the wires that helps the injector work is not doing its job right.
The code indicates an electrical issue with the high-pressure fuel injector for cylinder 12. It suggests a short circuit in the wiring or a problem with the injector itself.
P315D is triggered when the Engine Control Module (ECM) detects an issue with the electrical circuit of the high-pressure injector for cylinder 12. This could be due to a short circuit between the low side of the injector and ground or a high resistance in the circuit.
• Engine misfire
• Poor fuel economy
• Check engine light on
• Faulty injector for cylinder 12
• Damaged wiring or connectors
• ECM malfunction
Injector: A device that sprays fuel into the engine's cylinders.
ECM: Engine Control Module, the computer that controls engine functions.
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for cylinder 12 injector.
• Test the injector for proper resistance and operation.
• Replace the injector for cylinder 12 if faulty.
• Repair or replace damaged wiring or connectors.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Injector tester
$200 - $600
Moderate
• BMW 7 Series
• Mercedes-Benz S-Class
• Audi A8
• Regular maintenance checks
• Inspect wiring harnesses periodically
• Use high-quality fuel
Engine Performance
• Avoid driving with a misfiring engine to prevent damage.
• Get the vehicle inspected by a professional mechanic.
• Consider regular engine diagnostics to catch issues early.
Check with your vehicle manufacturer for warranty coverage on injectors and ECM.
This code is more common in high-performance vehicles with complex fuel systems.
Moderate – Address the issue soon to prevent engine damage.
Driving with a misfiring engine can lead to increased emissions and potential engine damage.
• Engine at operating temperature
• Vehicle in park or neutral
The injector for cylinder 12 is located on the engine block, typically near the intake manifold.
Q: Can I drive with a P315D code?
A: It's not recommended to drive with this code as it can lead to engine damage.
Q: How can I prevent injector issues?
A: Regular maintenance and using high-quality fuel can help prevent injector problems.
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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.