OBD
P0859
Traction Control Input Signal High
What it means
P0859 means Traction Control Input Signal High.
Check these first
- An open in the traction control input wire
- A traction control switch stuck open
- A wheel speed sensor that reads high
- A signal wire shorted to voltage
What to do next
- Read traction control input voltage
- Test the input wire for an open
- Test the input wire for a short to voltage
- Compare the wheel speed sensors
- Replace the switch if the signal stays high
- Clear the code and retest
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Updated
Generic SAE J2012 definition. Last updated 2026-10-10.