P0859 Traction Control Input Signal High

P0859 indicates a high traction control input signal. The traction request or status path is stuck high, open, or above the expected range.

Code status

Needs verification

Not yet verified against SAE J2012_202509 / J2012DA. Treat unverified rows as a lookup aid, not repair authority.

System: Transmission
Scope: iso-sae-controlled-p0
Standard: SAE J2012 / ISO 15031-6
Source: legacy-import

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not assume a high traction input is a transmission fault; verify the ABS and network source first.

Useful checks before replacing parts

Measure the traction input circuit where applicable and compare networked traction status across ABS, powertrain, and transmission modules.
Inspect for short-to-voltage faults, open grounds, connector corrosion, ABS communication problems, and traction switch issues.
Review whether the high input forces torque reduction, stability-control warnings, altered shifts, or limp mode.

Related OBD-II codes

These nearby transmission entries can help compare wording and fault area. They may share the same verification status as the source database.