Troubleshooting by Diagnostic Trouble Code (DTC) - DTC P0120/P0121/P0122/P0123
DESCRIPTION AND OPERATION
The Throttle Position Sensor (TPS) is installed on the wall of the throttle body and is connected to the throttle valve shaft. The TPS is a variable resistor (potentiometer) whose resistance changes according to the throttle valve position. When the accelerator pedal is depressed, the sensor resistance decreases. When the accelerator pedal is released, the sensor resistance increases.
The Engine Control Module (ECM) supplies a reference voltage to the Throttle Position Sensor (TPS) and then measures the voltage in the sensor signal circuit. Based on the sensor signal, the ECM adjusts the fuel injector pulse width and ignition timing. The TPS signal, together with the Manifold Absolute Pressure (MAP) sensor signal, is used by the ECM to determine engine load.
DTC SET CONDITIONS
The ECM will store DTC P0121 and illuminate the Malfunction Indicator Lamp (MIL) if the engine load data from the Manifold Absolute Pressure (MAP) sensor and the Throttle Position Sensor (TPS) do not agree. This DTC indicates that the engine load data (throttle position and intake air flow) measured by the TPS, the MAP sensor, or the ECM does not correspond to the expected load value.
The ECM will store DTC P0122 and illuminate the MIL if, within 0.2 seconds during two driving cycles, the sensor signal corresponds to a throttle valve opening angle of 2.1 degrees or less. This DTC indicates that the throttle valve opening angle measured by the TPS or the ECM is abnormally low.
The ECM will store DTC P0123 and illuminate the MIL if, within 0.2 seconds during two driving cycles, the sensor signal corresponds to a throttle valve opening angle greater than 105.4 degrees. This DTC indicates that the throttle valve opening angle measured by the TPS or the ECM is abnormally high.
The standard resistance between terminals 2 and 3 of the Throttle Position Sensor (TPS) connector is 1600 - 2500 Ω.
WIRING DIAGRAM
INSPECTION PROCEDURE
INSPECTION PROCEDURE
Test yourself
A quick Hyundai Elantra CN7 quiz: every answer comes with an explanation and a link to the manual page.