The throttle position sensor (TPS), is an electronic component that helps the engine computer determine the optimal ignition timing and fuel injector. This is done by measuring how open the throttle valve actually is. As a failsafe measure, vehicles with electronic throttle control use two throttle position sensor. The throttle position (TPS), which is a potentiometer on the throttle body, is used to detect if the engine computer has received a signal that exceeds the maximum limit. The sensor monitors the angle of the blades on the throttle valve and sends this data to the throttle control module or powertrain control module. The P0123 code is set if the sensor’s signal exceeds the threshold determined by the engine manufacturer for a period of time (more that 2 seconds) and the voltage level goes above 4.54 volts.
Note that ETC vehicles also use two accelerator pedal position sensors (APP) to determine how hard the pedal is pressed. If the TPS sensor is not working properly, then the P0123 code will be displayed in some vehicles.
Other fault codes related the TPS sensor: P0120, P0121, P0122, P0124
Table of Contents
What are the causes of fault code P0123?
- Faulty accelerator pedal sensor
- Problems with the throttle/pedal sensor circuit (e.g. damaged cables and loose connectors)
- Short circuit in TPS voltage signal
- The TPS sensor is not correctly installed
- A dirty or defective throttle body
- Faulty PCM/ECM/ECU
What are the symptoms of fault code P0123?
The PCM may cut the current to throttle valve adjustment elements, reducing the opening of the throttle plate to less than six degrees. This will put the vehicle in safe mode. Symptoms may vary depending on how the PCM is programmed by the vehicle manufacturer.
- Engine fault light illuminated
- Engine hesitating when accelerating
- Unregular engine operation
- Increased idle speed
- Stall of the vehicle
- When the vehicle is in safe mode, you can drive it very slowly and with limited throttle response.
How to Fix Fault Code P0123?
- Clear the codes and retest the vehicle to see if it returns.
- Repair damaged cables and loose connectors.
- Compare the data from TPS circuits B and A. If the comparison is incorrect, carry out TPS pinpoint testing according to manufacturer’s instructions.
- Replace the TPS sensor that is faulty.
How serious is fault code P0123?
The PCM may put the vehicle in safe mode due to the fault code P0123, which could cause various driving issues. According to the manufacturer’s safety mode strategy, you may experience problems with your vehicle such as stalling, a lack of acceleration, a high idle speed or a hesitation when accelerating. The engine may be damaged if the vehicle is used in this condition for a long time. The fault must therefore be identified and fixed as quickly as possible.
