DTC P0638; Pcm Throttle Valve Actuator Control Range/Performance Problem: Notes

WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

DETECTION CONDITION & POSSIBLE CAUSE

DTC P0638:00	Throttle valve actuator control range/performance problem
DETECTION CONDITION	The PCM compares the actual TP with the target TP. If the difference is more than the threshold value, the PCM determines that there is a throttle valve actuator control range/performance problem. Diagnostic support note This is a continuous monitor (CCM). The check engine light illuminates if the PCM detects the above malfunction condition during the first drive cycle. FREEZE FRAME DATA (Mode 2)/Snapshot data is available. DTC is stored in the PCM memory.
FAIL-SAFE FUNCTION	Restricts the upper limit of the engine speed. Stops the drive-by-wire control (throttle valve is open at approx. 8 ° by return spring force).
POSSIBLE CAUSE	Throttle body connector or terminals malfunction Short to ground in wiring harness between the following terminals: Throttle body terminal E-PCM terminal 1CG Throttle body terminal F-PCM terminal 1CC PCM connector or terminals malfunction Short to power supply in wiring harness between the following terminals: Throttle body terminal E-PCM terminal 1CG Throttle body terminal F-PCM terminal 1CC Open circuit in wiring harness between the following terminals: Throttle body terminal E-PCM terminal 1CG Throttle body terminal F-PCM terminal 1CC Throttle valve actuator malfunction Throttle valve malfunction PCM malfunction