Invalid Data Received From Transmission Control Module
What does U0402 mean?
The U0402 code means the vehicle's onboard diagnostic system has detected: Invalid Data Received From Transmission Control Module. This is a moderate severity code.
Common Symptoms
- Harsh or delayed gear shifts
- Transmission warning light on
- Vehicle stuck in limp mode (single gear)
- Speedometer reading incorrectly
- Check Engine Light illuminated
Probable Causes (Ranked by Likelihood)
- Failing TCM sending corrupted shift data Very High
- CAN bus wiring fault between TCM and ECM High
- Intermittent TCM connector issue Moderate
- TCM internal fault from overheating Moderate
Step-by-Step Diagnostic Procedure
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Check TCM connector for loose or corroded pins
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Monitor transmission live data for erratic values
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Inspect CAN bus wiring between TCM and ECM
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Check TCM power and ground connections
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Verify transmission fluid level and condition
Frequently Asked Questions
Can I drive with code U0402?
Drive only short distances. Invalid transmission data can cause harsh shifts or leave the vehicle stuck in a single gear.
What causes U0402?
Usually a failing TCM sending corrupted data, or a wiring fault between the TCM and ECM. Heat exposure can accelerate TCM failure on some vehicles.
Is U0402 expensive to fix?
Expect $200 to $900. TCM replacement with reprogramming is on the higher end. Wiring and connector repairs are less expensive.