AutoCodes – Generic – P0738

P0738 Code - TCM Engine Speed Output Circuit Low

Quick Answer

The Transmission Control Module (TCM) monitors the engine speed signal through the engine output speed sensor (turbine sensor). Common causes include Faulty Engine Output Speed Sensor, Engine Output Speed Sensor harness is open or shorted, Engine Output Speed Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0738 indicates TCM Engine Speed Output Circuit Low.
Common causes: Common causes include Faulty Engine Output Speed Sensor, Engine Output Speed Sensor harness is open or shorted, Engine Output Speed Sensor circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 4,266

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Apr 23, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0738 Description

The Transmission Control Module (TCM) monitors the engine speed signal through the engine output speed sensor (turbine sensor). The TCM sets the OBDII code when the engine speed output sensor signal is not to factory specifications.

OBDII Code P0738 - TCM Engine Speed Output Circuit Low - AutoCodes.com — P0738 Code - TCM Engine Speed Output Circuit Low

What does this mean?

What are the Possible Causes of the DTC P0738?

Faulty Engine Output Speed Sensor
Engine Output Speed Sensor harness is open or shorted
Engine Output Speed Sensor circuit poor electrical connection
Faulty Crank Shaft Position Sensor

How to Fix the DTC P0738?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0738 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0738 code?

Need more information on how to fix the P0738 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0738 code diagnosed by a professional: Find a repair shop in your area

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0738 Code

1. What are the common symptoms of OBDII code P0738 (TCM Engine Speed Output Circuit Low)?

The common symptoms of code P0738 may include issues with shifting gears, delayed or harsh shifting, poor fuel economy, and the illumination of the Check Engine Light.

2. What are the possible causes of OBDII code P0738?

Possible causes of code P0738 include a faulty transmission control module (TCM), damaged wiring or connectors in the engine speed output circuit, a defective engine speed sensor, or internal transmission issues.

3. How can I diagnose OBDII code P0738?

Diagnosing code P0738 typically involves using a diagnostic scanner to retrieve the code, checking the wiring and connectors in the engine speed output circuit, performing tests on the engine speed sensor, and inspecting the TCM for faults.

4. What should I do if I get OBDII code P0738?

If you get code P0738, it is recommended to have your vehicle inspected by a qualified mechanic to accurately diagnose the issue. Ignoring this code can lead to further transmission problems and potential safety risks.

5. Can I still drive my vehicle with OBDII code P0738?

It is not recommended to drive your vehicle with an active P0738 code, as it can lead to transmission issues and potential damage. It's best to address the problem promptly to prevent further complications.

6. How much does it cost to repair OBDII code P0738?

The cost of repairing code P0738 can vary depending on the underlying cause of the issue. Repair costs may include replacing the TCM, repairing wiring or connectors, replacing the engine speed sensor, or addressing internal transmission problems.

7. Are there any DIY tips for fixing OBDII code P0738?

While some basic inspections like checking for loose or damaged wiring can be done DIY, it is recommended to seek professional help for diagnosing and repairing code P0738 due to the complexity of transmission systems.

8. Can a low battery voltage trigger OBDII code P0738?

Yes, a low battery voltage can sometimes cause erratic behavior in the TCM, leading to the triggering of code P0738. Ensuring your vehicle's battery is in good condition is important for proper TCM operation.

9. How long does it take to repair OBDII code P0738?

The repair time for code P0738 can vary depending on the complexity of the issue and the availability of parts. Some repairs may be completed in a few hours, while more extensive repairs could take longer.

10. Is it possible for OBDII code P0738 to reoccur after repair?

Yes, it is possible for code P0738 to reoccur if the underlying issue was not fully resolved during the initial repair. It is important to ensure that all recommended repairs are completed to prevent the code from coming back.