Invalid Data Received From Transmission Control Module
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.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $200 - $900 (parts and labor)
Network codes mean modules are not communicating. You need a scanner that reads all systems to find the problem.
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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
-
Check TCM connector for loose or corroded pins
-
Monitor transmission live data for erratic values
-
Inspect CAN bus wiring between TCM and ECM
-
Check TCM power and ground connections
-
Verify transmission fluid level and condition
Common Fixes by Vehicle
What techs usually find when diagnosing U0402 on specific vehicles — tap your vehicle for the fix and the exact part:
2003-2014 Chevrolet Silverado/GMC Sierra hard DIY
U0402 (invalid data from TCM) on GM trucks means the ECM sees the transmission control module reporting but with bad data. Common causes: failing TCM internally, low voltage at the TCM, or bad programming after an update. Start by loading the latest TCM calibration (tech2Win or dealer). If that does not clear it and voltage at the TCM is stable, replace and reprogram the TCM.
Labor: 1-3 hours2007-2014 Ford F-150 hard DIY
F-150 U0402 often appears when the transmission is going into limp mode. The TCM is sending data but the data is implausible (for example, gear ratio impossible or output shaft speed out of range). Pull transmission codes with FORScan in addition to generic OBD-II. Often a transmission range sensor or output shaft speed sensor is the real cause -- the TCM is innocent.
Labor: 1-3 hours2005-2012 Dodge Ram 1500 hard DIY
Ram U0402 can be a symptom of TIPM issues affecting TCM power, or an internal TCM fault. Check the TCM fuse and relay in the TIPM first. Verify 12V at the TCM with key on. If power is good and U0402 persists alongside transmission complaints, the TCM may need replacement. On 5-speed 545RFE trucks, the TCM is internal to the transmission and requires trans removal to service.
Labor: 2-4 hoursFrequently 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.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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