What Does U0402 Mean?
The receiving module detects that data from the Transmission Control Module (TCM) is invalid, illogical, or out of acceptable range. This is a network communication data integrity issue, not necessarily a transmission mechanical problem.
Common Causes
35%
Failing TCM producing corrupted output data
30%
CAN bus wiring problems between TCM and other modules
20%
TCM power or ground circuit issues affecting module operation
10%
Software incompatibility or outdated TCM calibration
5%
Internal sensor failure in transmission sending bad data to TCM
Diagnostic Steps
1
Step 1: Monitor TCM data PIDs in real-time, looking for implausible values (e.g., gear ratio errors, speed sensor mismatches)
2
Step 2: Check TCM power supply voltage and ground integrity at module connector
3
Step 3: Inspect transmission harness connector for corrosion, damaged pins, or moisture intrusion
4
Step 4: Test CAN bus signal quality at TCM connector using oscilloscope (look for proper voltage swings and waveform)
5
Step 5: Check for TCM software updates or reflash procedures in service bulletins
Estimated Repair Cost
$100 - $1,500
Parts + labor, varies by vehicle and location
The receiving module detects that data from the Transmission Control Module (TCM) is invalid, illogical, or out of acceptable range. This is a network communication data integrity issue, not necessarily a transmission mechanical problem.
The most common cause of U0402 (Invalid Data Received From Transmission Control Module) is: Failing TCM producing corrupted output data
Typical repair costs for U0402 range from $100 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
May cause harsh shifting, inability to shift gears, transmission stuck in one gear, or complete loss of drive. Vehicle may enter fail-safe mode.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0402 to identify the root cause.
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Quick Info
Category
Network
System
Transmission Control/Network Communication
Difficulty
Type
Generic (SAE)
Recommended Tools
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