A vehicle’s traction control system is engineered to momentarily interrupt engine power, then use the ABS braking system to prevent wheel-spin in slippery conditions. The presence of a P0859 DTC means that there is an unusually high voltage input signal coming from the traction control system. This can prevent the traction control system from working, and negatively impact the safety of your vehicle.
How Serious is the Code?
A P0859 diagnostic trouble code one of the most severe OBDII trouble codes, because it relates to a very important safety system. The presence of this code generally means that the traction control system will not work, so you should exercise extreme care when driving in low traction conditions. And you should also see a mechanic as soon as possible.
Symptoms of a P0859 include:
- Traction control system no longer functions
- Erratic shifting
- Limp mode
- Damaged wiring or corroded connectors
- Bad traction control switch
- Bad electronic brake control module/ABS module
- Bad traction control module
How to Diagnose the Code?
The first step in mechanic should take when diagnosing a P0859 OBDII trouble code, is to thoroughly examine the condition of the wiring and connectors. If there is an on/off switch for the traction control system, it should be checked for signs of water damage and corrosion on the connectors. Should no problems be found up to this point, the traction control module and ABS module will need to be considered as possible causes of this code.
What Repairs Will Fix P0859?
- Repair or replace damaged wiring and/or connectors
- Replace traction control switch
- Replace traction control module
- Replace electronic brake control module / ABS control module