DTC Advanced Diagnostics: P0121
DTC P0121:Throttle Position (TP) Sensor A Out of Range

General Description

The electronic throttle control system controls the throttle valve opening. The system includes the throttle actuator, the throttle valve, throttle position (TP) sensors A and B, the PGM-FI subrelay circuit, the accelerator pedal position (APP) sensor, and the powertrain control module (PCM). TP sensor A is a semiconductor type, and it is attached to the throttle body and shaft to determine throttle valve position. The throttle valve position signal from TP sensor A is transmitted to the PCM for target position feedback control. If the signal voltage from TP sensor A is a set value for a specified time, the PCM detects a TP sensor A malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Continuous
Sequence
None
Duration
6 seconds or more
DTC Type
Two drive cycles, MIL on

Enable Conditions
Condition
 
Vehicle
ON mode

Malfunction Threshold
The TP sensor A output voltage [TP SENSOR A] is 0.38 V or less, or 4.50 V or more for at least 6 seconds.

[ ]: HDS Parameter

Possible Cause
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
Throttle body internal failure (TP sensor A)
PCM internal circuit failure

Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.