What does code P05C9 mean?

Q: What does code P05C9 mean?

Economy Mode Switch Circuit Low. P05C9 indicates that the powertrain control module has detected a low-voltage condition on the economy mode switch circuit, meaning the signal wire is reading near ground when it should be at a higher reference voltage. The economy mode switch, often part of a driver-selectable driving mode system, allows the driver to toggle between economy and normal performance settings, and this code sets when the circuit is shorted to ground or the switch is stuck closed.

DTC codes / P05xx · Vehicle speed, idle control and auxiliary inputs / P05C9

P05C9Economy Mode Switch Circuit Low

P05C9 indicates that the powertrain control module has detected a low-voltage condition on the economy mode switch circuit, meaning the signal wire is reading near ground when it should be at a higher reference voltage. The economy mode switch, often part of a driver-selectable driving mode system, allows the driver to toggle between economy and normal performance settings, and this code sets when the circuit is shorted to ground or the switch is stuck closed.

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.