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U0402 — Invalid Data from TCM
SeriousNetwork/CANPower derate likely — plan to stop soon
Seen on: Heavy Truck
Invalid Data from TCM. Common causes: TCM sending invalid CAN data.
Don't risk it — get a diesel tech on the truck.
Your code rides along, so nearby mechanics see the fault before they quote you.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- TCM sending invalid CAN data
- TCM internal fault
- software version mismatch
First moves (roadside)
- Check TCM software level
- update or replace TCM
FAQ
What does U0402 mean?
Invalid Data from TCM. Common causes: TCM sending invalid CAN data.
How serious is U0402?
Serious — Power derate likely — plan to stop soon.
What's the most likely cause of U0402?
The most common cause is: TCM sending invalid CAN data. Other possibilities include TCM internal fault; software version mismatch.
Can I keep driving with U0402?
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Throwing this code right now?
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.