DTC P0638-00: Throttle Valve Actuator Control System: Characteristic Malfunction

P0638-00: (PCM - VIN Y) DETECTION CONDITION AND POSSIBLE CAUSE

System malfunction location	Throttle valve actuator control system: Characteristic malfunction
Detection condition	Difference between the actual and target throttle positions is the specification or more.
Fail-safe	Restricts the upper limit of the engine speed. Fixes the throttle valve opening angle.
Possible cause	Malfunction in wiring harness (including connector/terminal) between throttle body and PCM (see CIRCUIT INSPECTION .) (see CONNECTOR INSPECTION .) Throttle valve actuator malfunction (Refer to THROTTLE BODY INSPECTION (VIN Y) in the service information.) Throttle body malfunction (throttle valve malfunction) (Refer to INTAKE-AIR SYSTEM REMOVAL/INSTALLATION (VIN Y) in the service information.) PCM malfunction (Refer to applicable PCM REMOVAL/INSTALLATION (VIN Y) in the service information.)
Repeatability verification procedure	Clear the DTC recorded in the memory. (see CLEARING DTC .) Perform the KOEO or KOER self test. (See DTC INSPECTION .)
Courtesy of MAZDA MOTORS CORP.
1	PCM
2	Throttle valve actuator (throttle body)