Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means the car's engine is trying to spin in the wrong direction, like trying to go backwards instead of forwards.
The engine control module (ECM) has detected that the engine is rotating in the opposite direction than intended.
P139F indicates that the engine's crankshaft is rotating in reverse. This can occur during startup or shutdown, and it may cause issues with the engine's timing and operation.
• Engine fails to start
• Unusual noises during engine shutdown
• Check Engine Light illuminated
• Faulty starter motor
• Incorrect ignition timing
• Damaged flywheel
Starter Motor: A device that rotates the engine to initiate its operation.
Flywheel: A mechanical device that stores rotational energy.
• Check for any stored trouble codes.
• Inspect the starter motor for faults.
• Verify the ignition timing settings.
• Replace or repair the starter motor.
• Adjust the ignition timing.
• Inspect and possibly replace the flywheel.
• OBD-II scanner
• Timing light
• Socket set
$200 - $600
Moderate
• Vehicle 1
• Vehicle 2
• Vehicle 3
• Regular maintenance of the starter motor
• Ensure proper ignition timing
• Routine checks of the flywheel
Engine Performance
• Do not attempt to start the vehicle repeatedly if the engine does not start.
• Seek professional assistance if unusual noises are heard during shutdown.
Check with the vehicle manufacturer for warranty coverage on engine components.
This code is relatively rare and often associated with specific engine configurations.
High – Immediate attention is required to prevent potential engine damage.
Operating a vehicle with this issue may lead to further engine damage and potential safety hazards.
• Engine at operating temperature
• Vehicle parked on a level surface
The starter motor is typically located near the bottom of the engine, while the flywheel is between the engine and transmission.
Q: Can I drive with a P139F code?
A: It's not recommended to drive with this code, as it may cause further engine damage.
Q: What happens if I ignore this code?
A: Ignoring this code can lead to severe engine damage and increased repair costs.
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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.
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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.