P2104 Subaru Electronic Throttle Control System Forced Idle

Possible causes

– Faulty Accelerator Position Sensor(APS)
– Faulty APS+Brake
– Faulty APS + Vehicle speed sensor
– Faulty APS + Vehicle speed sensor + Brake
– Faulty Electronic Throttle Control(ETC) Items(TPS or ETC motor etc)
– Faulty Powertrain Control Module (PCM)

Symptoms

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

P2104 Subaru Description

The Electronic Throttle Control(ETC) system is made of the components throttle body, Throttle Position Sensor(TPS)1&2 and Accelerator Position Sensor(APS) 1&2. The throttle body contains the actuator, the throttle plate and the throttle position sensor (potentiometer), which are integrated in one housing. The actuator consists of a DC motor with a two-stage gear. The opening angle of the throttle valve is detected by the throttle position sensor which is mounted on the throttle body. And it provides feedback to the Powertrain Control Module (PCM) to control the throttle motor in order to control the throttle valve opening angle properly in response to the driving condition.