Possible causes

– Drive-by-wire control system malfunction
– Throttle actuator malfunction
– Throttle valve malfunction
– PCM malfunction

Tech notes

Dirty or clogged throttle body can triggered the P0638 code. Before replacing any parts try cleaning the throttle body and reset the engine light.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P0638 Description

The Powertrain Control Module (PCM) compares the actual Throttle Possition (TP) with the target TP when the engine is running. If the difference is more than the specification, the PCM determines that there is a throttle actuator control circuit range/performance problem.

P0638 Information for specific makes

P0638 HYUNDAI
P0638 KIA
P0638 MAZDA
P0638 MINI
P0638 MITSUBISHI
P0638 SUBARU
P0638 SUZUKI
P0638 VOLKSWAGEN
P0638 VOLVO