Fault Family System: Powertrain (P-Codes) 4 SAE Codes

Traction Control Input Signal Circuit

Diagnostic & Technical Explanation

Code P0856 (Traction Control Input Signal) sets when the ECM/TCM sees an open, shorted, or implausible signal on the traction-control-system input line used to request torque reduction or shift adjustments during wheel slip. Causes are a network wiring fault between the ABS/traction module and ECM/TCM, a corroded connector, or an internal fault in the requesting module.

These 4 diagnostic trouble codes share one detection mechanism and one repair path, which is why MechanicDB groups them into a single authored fault family rather than repeating the same explanation 4 times.

Codes in this family (4)

Code	Definition	Repair coverage
P0856	Traction Control Input Signal	3 ranked fixes
P0857	Traction Control Input Signal Range/Performance	3 ranked fixes
P0858	Traction Control Input Signal Low	3 ranked fixes
P0859	Traction Control Input Signal High	3 ranked fixes

What this page does not show

This page publishes the fault mechanism and the code index. The licensed dataset adds, for every one of the 15,886 codes, the full authored repair set (56,729 procedures in total) with the fields deliberately withheld here:

Procedures 2..n after the first-listed procedure
Aftermarket parts cost ranges in USD (est_parts_cost_min/max_usd)
Professional labor-hour estimates (est_labor_hours)
Step-by-step diagnostic and repair instructions
Replacement-part mappings and catalog lookups
6,637 manufacturer-specific OEM codes across 32 makes ($149 tier)

Need All 15,886 Codes as Data?

Pipe-delimited CSV, Apache Parquet and a relational SQLite database, with commercial application rights and instant download. Built for scan tools, shop software and research - not assembled one web page at a time.

License OEM Complete · $149 Standard (SAE only) · $49

$49 Standard: 9,249 SAE codes · $149 OEM Complete: all 15,886 codes, including 6,637 OEM codes across 32 makes · $149 Heavy Duty: 4,212 fault pairs (J1939) · one-time · compare tiers