The accelerator pedal position sensor is installed on the upper endof the accelerator pedal assembly. The sensor detects the accelerator position and sends a signal to the ECM.Accelerator pedal position sensor has two sensors. These sensorsare a kind of potentiometers which transform the accelerator pedalposition into output voltage, and emit the voltage signal to the ECM.In addition, these sensors detect the opening and closing speed ofthe accelerator pedal and feed the voltage signals to the ECM. TheECM judges the current opening angle of the accelerator pedal fromthese signals and controls the throttle control motor based on thesesignals.Idle position of the accelerator pedal is determined by the ECMreceiving the signal from the accelerator pedal position sensor. The ECM uses this signal for the engine operation such as fuel cut

If DTC P2138 is displayed with DTC P1229, first perform the trouble diagnosis for DTC P1229.