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 electrical part that helps control how much fuel goes into one of the engine's cylinders. It's like a light switch that's stuck in the 'on' position when it shouldn't be.
The P3138 code indicates an issue with the electrical circuit that controls the fuel injector for cylinder 10. The circuit is reading a higher voltage than expected, which suggests a possible electrical fault.
The P3138 code is triggered when the Engine Control Module (ECM) detects a high voltage condition in the low side circuit of the high-pressure fuel injector for cylinder 10. This could be due to a short to voltage, a faulty injector, or an ECM issue.
• Check Engine Light is on
• Engine misfire
• Poor fuel economy
• Faulty fuel injector
• Short to voltage in the injector circuit
• Faulty Engine Control Module (ECM)
ECM: Engine Control Module
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 10 injector.
• Test the injector for proper operation.
• Repair or replace damaged wiring or connectors.
• Replace the faulty injector.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Fuel injector tester
$200 - $600
Moderate
• BMW 7 Series
• Audi A8
• Mercedes-Benz S-Class
• Regular maintenance of the fuel system
• Use quality fuel
• Inspect electrical connections periodically
Engine Performance
• Avoid driving the vehicle until repaired to prevent further damage.
• Consult a professional mechanic for a thorough diagnosis.
Check if the vehicle is still under warranty for powertrain components.
This code is more common in vehicles with direct fuel injection systems, particularly in high-performance engines.
Moderate – It should be addressed soon to avoid potential engine damage.
Driving with a misfiring engine can lead to increased emissions and potential safety hazards.
• Engine running
• Under load conditions
The fuel injector for cylinder 10 is located on the engine block, typically near the intake manifold.
Q: Can I drive with a P3138 code?
A: It's not recommended to drive with this code, as it can cause engine damage and poor performance.
Q: How can I prevent this code from appearing?
A: Regular maintenance and using quality fuel can help prevent injector issues.
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.
View on Amazon
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.
View on Amazon
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.
View options on Amazon
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.