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 the computer in the car is not getting the right signal from the part that controls when the engine's spark plugs fire. It's like if your remote control wasn't sending the right signal to your TV.
The P038B code indicates that the ignition control module is sending a signal that is lower than expected to the engine control module (ECM).
The P038B code is triggered when the Engine Control Module (ECM) detects a low voltage condition in the ignition I control signal circuit. This circuit is responsible for managing the timing of the ignition system, ensuring that the spark plugs fire at the correct time for optimal engine performance. A low signal could be due to wiring issues, a faulty ignition control module, or other related components.
• Check Engine Light is on
• Engine misfires
• Poor fuel economy
• Faulty ignition control module
• Damaged wiring or connectors in the ignition circuit
• ECM malfunction
ECM: Engine Control Module
Ignition Control Module: A component that manages the timing of the ignition system
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors related to the ignition control circuit.
• Test the ignition control module for proper operation.
• Repair or replace damaged wiring or connectors.
• Replace the faulty ignition control module.
• Update or reprogram the ECM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $500
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regularly inspect and maintain ignition system components.
• Ensure all electrical connectors are secure and corrosion-free.
• Perform routine vehicle diagnostics.
Engine Performance
• Do not ignore the Check Engine Light; get it diagnosed promptly.
• Regular maintenance can prevent ignition system issues.
• Consult a professional mechanic if unsure about repairs.
Check with your vehicle's manufacturer for warranty coverage on ignition system components.
This code has been associated with ignition system issues in various vehicles, often due to aging components or poor maintenance.
Moderate – While the vehicle may still be drivable, it is important to address this issue soon to avoid further engine performance problems.
Driving with a malfunctioning ignition system can lead to increased emissions and potential safety risks. Ensure repairs are done by a qualified professional.
• Engine must be running.
• Vehicle should be at normal operating temperature.
The ignition control module is typically located near the engine, often mounted on or near the engine block or firewall.
Q: Can I drive with a P038B code?
A: While you may be able to drive, it's not recommended as it can lead to further engine problems.
Q: How do I reset the Check Engine Light after fixing the issue?
A: After repairing the issue, use an OBD-II scanner to clear the code and reset the light.
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.