What does code P0579 mean?

DTC codes / P05xx · Vehicle speed, idle control and auxiliary inputs / P0579

P0579Cruise Control Multi-Function Input 'A' Circuit Range/Performance

P0579 indicates that the cruise control multi-function input 'A' circuit has a range or performance problem, meaning the powertrain control module (PCM) sees a signal voltage from the cruise control switch that is outside the expected range or behaves erratically. The PCM monitors this input to determine driver commands such as set, resume, accelerate, and coast, and it sets the code when the voltage does not match any valid command or changes too quickly.

SystemPowertrain

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.