P0121

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

HINT: This is the purpose of the throttle position sensor.


CIRCUIT DESCRIPTION

DTC Detection Condition:

The throttle position sensor is mounted in the throttle body and detects the throttle valve opening angle.detects the throttle valve opening angle.

When the throttle valve is fully closed, a voltage of approximately 0.3 to 0.8 V is applied to terminal VTA of the ECM. The voltage applied to terminal VTA of the ECM increases in proportion to the opening angle of the throttle valve and becomes approximately 3.2 to 4.9 V when the throttle valve is fully opened. The ECM judges the vehicle driving conditions from these signals input from terminal VTA, uses them as one of the conditions for correct the air-fuel ratio correction, power increase correction and fuel cut control etc.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Condition:

Typical Malfunction Thresholds:

Component Operating Range:

The throttle position sensor varies its resistance with the angle of the throttle valve. The ECM applies a regulated reference voltage to the throttle position sensor "+: VC" terminal and calculates the angle of the throttle valve based on the voltage present at the throttle position sensor "signal: VTA" terminal.

When the throttle valve is near the fully closed position, the output voltage of the throttle position sensor is low. When it is near the fully open position, the output voltage is high.

The ECM checks the indicated angle of the throttle valve during "stop and go" conditions. If the indicated angle (or voltage) in the "closed throttle" position is out of the specified range (4 times or more), the ECM interprets this as a malfunction in the throttle position sensor and sets a DTC.

Step 1:

INSPECTION PROCEDURE

HINT: Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a 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.