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 computer is having trouble reading the position of the crankshaft, which is a part that helps the engine run smoothly.
The engine control module (ECM) is not receiving a consistent signal from the crankshaft position sensor, which is crucial for timing the engine's functions.
The P138F code is triggered when the ECM detects an irregular signal from the crankshaft position sensor. This sensor monitors the position and rotational speed of the crankshaft, which is essential for engine timing and fuel injection. A synchronization error indicates that the signal is not matching expected patterns, possibly due to sensor malfunction or wiring issues.
• Engine misfires
• Poor acceleration
• Check Engine Light is on
• Faulty crankshaft position sensor
• Damaged or corroded wiring or connectors
• ECM software issue
ECM: Engine Control Module, the computer that controls engine functions.
Crankshaft: A rotating shaft in the engine that converts linear piston motion into rotational motion.
• Use an OBD-II scanner to verify the code.
• Inspect the crankshaft position sensor and its wiring for damage.
• Test the sensor's output with a multimeter.
• Replace the crankshaft position sensor if faulty.
• Repair or replace damaged wiring or connectors.
• Update or reprogram the ECM if necessary.
• OBD-II scanner
• Multimeter
• Socket set
$150 - $300
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regularly inspect engine wiring for damage.
• Keep the engine bay clean to prevent corrosion.
• Perform regular maintenance checks.
Sensor Issue
• Do not ignore the Check Engine Light.
• Seek professional diagnosis to prevent further damage.
Check with your vehicle manufacturer; sensor-related issues may be covered under powertrain warranty.
This code has been associated with sensor failures and wiring issues in various vehicle models over the years.
Moderate – It should be addressed soon to prevent engine performance issues.
Driving with a malfunctioning crankshaft position sensor can lead to safety issues due to potential engine stalling.
• Engine at operating temperature
• Vehicle stationary
The crankshaft position sensor is typically located near the engine's crankshaft, often at the front or side of the engine block.
Q: What happens if I ignore this code?
A: Ignoring this code can lead to poor engine performance and potential engine damage.
Q: Can I drive my car with this code?
A: It's not recommended to drive for long periods with this code, as it may cause engine stalling or misfires.
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Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
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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.