P2123 - THROTTLE / PEDAL POSITION SENSOR / SWITCH "D" CIRCUIT HIGH

DTC P2123 OBDII code setting indicates that the Powertrain Control Module (PCM) detected a high voltage input in the Throttle Position Sensor (TPS) circuit. The “D” description refers to a particular area of a circuit or sensor. For this reason, you should consult a reliable source of information about your vehicle for details. This code is only set on vehicles equipped with Drive-By-Wire systems (DBW).

DBW systems are controlled by the PCM, through a throttle motor actuator, and multiple Throttle Position Sensors. The sensors typically have a 5-volt reference and ground signal. These sensors are potentiometers that complete the corresponding circuit. Their resistance varies in response to the movement made by the circuit board contacts and this causes fluctuations in the circuit resistance and signals input voltage to the PCM.

If the input voltage exceeds the limit set by the manufacturer for more than a certain time, this code is set and the Check Engine light illuminates.

• Malfunction Indicator Lamp (MIL) on.
• Throttle sticks.
• Acceleration is limited.
• Cruise control does not work.

The reasons for the P2123 OBD2 diagnostic code being set are:

• The circuit between the Throttle Position Sensor and the Powertrain Control Module could be open or shorted.
• The TPS sensor may be faulty.
• System wiring or connectors may be damaged.
• The DBW system actuator motor could be defective.

The steps to follow for proper diagnosis of the P2123 OBDII trouble code are as follows:

• Check the Technical Service Bulletins that are available for your vehicle.
• Thoroughly inspect the cables and connectors related to the system. Repair or replace any of these components that are damaged.
• Check the throttle plate for carbon buildup. If this is the case, clean it.
• Use a DVOM to check the operation of the Throttle Position Sensor Operate the throttle slowly from the closed position to the open position. If you detect voltage irregularities, replace the TPS sensor.