Troubleshooting

DTC P0121 THROTTLE/PEDAL POSITION SENSOR/SWITCH "A" CIRCUIT RANGE/PERFORMANCE PROBLEM

CIRCUIT DESCRIPTION

DTC Detecting Condition:

Throttle position sensor is mounted on the throttle body and it has 2 sensors to detect the throttle opening angle and the malfunction of the throttle position sensor's own.

The voltage applied to terminals VTA1 and VTA2 of the ECM changes between 0 V and 5 V in proportion to the opening angle of the throttle valve.

The ECM judges the current opening angle of the throttle valve from these signals input from terminals VTA1 and VTA2, and the ECM controls the throttle motor to make the throttle valve angle properly in response to the driving condition.

If this DTC is stored, the ECM cuts the power down for the throttle motor, and the throttle valve is fully closed by the return spring.

INSPECTION PROCEDURE

HINT: Read freeze frame data using hand-held tester or OBD II scan tool. Because freeze frame records the engine conditions when the malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.

REPLACE E.F.I. THROTTLE POSITION SENSOR