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 car's computer is having trouble getting a steady signal from a sensor that helps it know the exact position of the engine parts. It's like trying to watch a movie with a skipping DVD.
The P0378 code is triggered when the engine control module (ECM) detects an intermittent or erratic signal from the high-resolution timing reference sensor B.
The high-resolution timing reference sensor B is responsible for providing precise engine position information to the ECM. This sensor helps the ECM control fuel injection and ignition timing. If the signal from this sensor is erratic or intermittent, it can cause the ECM to miscalculate engine timing, leading to performance issues.
• Check Engine Light is on
• Engine misfires
• Poor engine performance
• Faulty high-resolution timing reference sensor B
• Damaged wiring or connectors in the sensor circuit
• ECM malfunction
ECM: Engine Control Module
OBD-II: On-Board Diagnostics, Second Generation
• Use an OBD-II scanner to confirm the code.
• Inspect the sensor and its wiring for damage.
• Test the sensor's signal with an oscilloscope.
• Replace the faulty sensor.
• Repair or replace damaged wiring or connectors.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Oscilloscope
$100 - $500
Moderate
• Chevrolet Silverado
• GMC Sierra
• Ford F-150
• Regular maintenance checks on sensors and wiring.
• Avoid exposure of engine components to excessive moisture.
• Ensure timely replacement of faulty sensors.
Sensor Issue
• Do not ignore the Check Engine Light.
• Get the vehicle inspected by a professional mechanic.
• Avoid driving the car aggressively until the issue is resolved.
Check your vehicle's warranty for coverage on engine sensors.
This code has been associated with sensor wear and tear over time, especially in older vehicles.
Moderate – It should be addressed soon to avoid potential engine performance issues.
Driving with a malfunctioning engine sensor can lead to increased emissions and potential safety hazards.
• Engine at operating temperature
• Vehicle in park or neutral
The high-resolution timing reference sensor B is typically located near the crankshaft or camshaft, depending on the engine design.
Q: Can I drive with a P0378 code?
A: It's not recommended to drive for extended periods with this code, as it can lead to engine performance issues.
Q: How do I clear a P0378 code?
A: After repairs, you can clear the code with an OBD-II scanner, but ensure the issue is fixed first.
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Universal · Digital multimeter
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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.