P0739: TCM Engine Speed Output Circuit High DTC Trouble Code

Sometimes called the crankshaft position sensor, the engine speed sensor monitors the speed of the crankshaft, so the ECU can use that data to determine shift points. A P0739 DTC means there was a higher than expected electrical signal coming from the sensor.

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What Transmission Do I Have?

How Serious is the Code?

The engine speed sensor is very important to the reliable operation of your engine and transmission, so having a P0739 diagnostic trouble code means that your vehicle will probably have serious drivability problems.

Symptoms

Symptoms of a P0739 include:

• Check engine light
• Erratic, delayed or harsh shifts
• Speedometer may appear broken
• Limp Mode
• Transmission not able to shift gears
• Engine misfire/hesitation
• Engine stalls
• Engine doesn’t start

Causes

• Malfunctioning engine output speed sensor / crankshaft position sensor
• Faulty output speed sensor
• Broken, loose or corroded connectors
• Frayed or shorted wiring
• Valve body or pressure related issues
• Broken shift solenoid
• ECU failure
• TCM failure

How to Diagnose the Code?

If the engine cranks, but will not start, then the engine output speed sensor will need to be tested. If the engine runs, then the transmission fluid should be checked for signs of metallic shavings, as they can affect the performance of the magnetic sensor head. Any ATF leaks will need to be repaired, along with damaged/frayed wiring, and corroded or broken connectors. TSB’s and software updates should be considered before testing the engine output speed sensor / crankshaft position sensor itself. If no issues are found by this point, then the TCM, solenoids or valve body should be analyzed.

Common Mistakes When Diagnosing

Believe it or not, dirty transmission fluid, or a transmission fluid leak can often be the cause of a P0739. If metal shavings in the dirty transmission fluid have become attached to the magnetic sensor head, then it won’t be able to function properly. ATF leaks can also cause a P0739, by corroding the wiring or connectors.

What Repairs Will Fix P0739?

• Change transmission fluid and filter
• Fix transmission fluid leaks
• Replace engine speed output sensor
• Replace transmission output speed sensor
• Repair or replace damaged wiring and/or connectors
• Replace solenoids

Related Codes

N/A

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What Transmission Do I Have?

Links To Diagnostic Codes

Links To Symptoms

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