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Engine-Codes – Generic – U0402

U0402 Code - Invalid Data Received From Transmission Control Module

Quick Answer

The U0402 diagnostic trouble code (DTC) indicates that the engine control module (ECM) has detected invalid data from the transmission control module (TCM). Common causes include Faulty wiring or connections between the ECM and TCM, Defective TCM or ECM, Corrosion or damage to electrical connectors. 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
U0402 indicates Invalid Data Received From Transmission Control Module.
Common causes
Common causes include Faulty wiring or connections between the ECM and TCM, Defective TCM or ECM, Corrosion or damage to electrical connectors.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 12, 2024
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Code U0402 Description

The U0402 diagnostic trouble code (DTC) indicates that the engine control module (ECM) has detected invalid data from the transmission control module (TCM). This communication error between the ECM and TCM can lead to various issues within the vehicle's transmission system. The TCM plays a crucial role in controlling the transmission's shifting patterns, torque converter lockup, and other functions essential for proper vehicle operation.

OBDII Code U0402 - Invalid Data Received From Transmission Control Module
U0402 Code - Invalid Data Received From Transmission Control Module

Common Causes of U0402

  1. Faulty wiring or connections between the ECM and TCM
  2. Defective TCM or ECM
  3. Corrosion or damage to electrical connectors
  4. Software issues or programming errors in the ECM or TCM
  5. Faulty sensors within the transmission system

Symptoms of U0402

  1. Erratic shifting or hesitation when changing gears
  2. Harsh engagement when shifting between gears
  3. Transmission slipping or inability to shift into certain gears
  4. Reduced fuel efficiency
  5. Illuminated check engine light

How to Fix U0402

  1. Begin by conducting a thorough inspection of the wiring harness and connectors between the ECM and TCM. Look for any signs of damage, corrosion, or loose connections. Repair or replace any damaged components as needed.
  2. Use a diagnostic scan tool to reset the code and clear any stored data in the ECM and TCM. This can sometimes resolve communication errors and eliminate the U0402 code.
  3. If the issue persists, consider updating the software in both the ECM and TCM to the latest available version. Manufacturers often release software updates to address communication issues and improve system performance.
  4. If none of the above steps resolve the problem, it may be necessary to replace either the ECM or TCM, depending on which component is found to be faulty. This should be done by a qualified technician to ensure proper installation and programming of the new module.

Cost to Fix U0402

The cost of repairing the U0402 code can vary depending on the specific cause of the issue and the labor rates in your area. In general, the cost of repairing a communication error between the ECM and TCM can range from $200 to $800, including parts and labor. However, this is just a rough estimate, and actual costs may be higher or lower depending on the extent of the repair needed. It's recommended to consult with a trusted auto repair shop for a more accurate cost estimate based on your vehicle's make and model. Keep in mind that labor rates can vary widely, so it's essential to shop around for the best deal.

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Code U0402 Information for Specific Makes

  • U0402 Buick — Invalid Data Received From Transmission Control Module
  • U0402 Cadillac — Invalid Data Received From Transmission Control Module
  • U0402 Chevrolet — Invalid Data Received From Transmission Control Module
  • U0402 Chrysler — Invalid Data Received From Transmission Control Module
  • U0402 Dodge — Invalid Data Received From Transmission Control Module
  • U0402 Ford — Invalid Data Received From Transmission Control Module
  • U0402 GMC — Invalid Data Received From Transmission Control Module
  • U0402 Infiniti — Invalid Data Received From Transmission Control Module
  • U0402 Jeep — Invalid Data Received From Transmission Control Module
  • U0402 Lincoln — Invalid Data Received From Transmission Control Module
  • U0402 Mercury — Invalid Data Received From Transmission Control Module
  • U0402 Nissan — Invalid Data Received From Transmission Control Module
  • U0402 RAM — Invalid Data Received From Transmission Control Module
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 U0402 Code

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  • my ford ranger auto transmission 3.2 4x4 model 2015 dont shift gears nor

    show the shift positions in meter except P being blinking and also

    reverse lights and cam not work and show fault code u0402 TCM on

    computer

    Reply to Comment