Fault code P0122 – a step-by-step guide to diagnosing and fixing it

DTC P0122 is triggered when the onboard computer has recognised that the throttle position sensor (TPS) circuit As voltage output is lower than the normal range. The sensor monitors the car throttle body's movement. As the component opens, it generates a voltage. This range will vary depending on the make of the vehicle, however, the code typically appears when the circuit voltage is below an 0.17– 0.2 V limit for 8 seconds or more.

• Installing the device incorrectly. This is a likely cause if it has recently been replaced or removed. Some devices have to be installed in a specific position or angle to function properly. There could also be problems if the device is not secure.
• A short or broken circuit in the power supply wire or signal wire.This could be due to harsh operating conditions causing damage to the wire’s insulation sheath.
• Corroded electrical contacts resulting from exposure to dirt or moisture. This can occur when the connector cable isn’t securely attached to the device.
• A damaged or faulty control module. Although this is rarely the cause, it shouldn’t be ruled out entirely before a diagnosis has been made.
• A fault with the TPS itself

• Activation of the check engine light
• Stalling or surging, particularly during gear changes
• A rough or high idle
• Hesitation or reduced acceleration
• A loss of engine power
• A decrease in fuel efficiency

• Run a diagnostic scan to see whether other DTCs are present. To do this, you will need to connect an OBD2 scan tool to the onboard computer via the data link connector port. This will help you to identify the exact cause of the fault. The codes can also be reset after each repair.
• Make sure that the TPS has been installed properly and make adjustments if necessary. Refer to the vehicle’s repair manual for specific instructions on how to install, adjust, or replace the component. Some devices come with a special adjustment screw.
• Replace any damaged or faulty wires and connectors, and clean the contacts to remove any rust. There are cleaning products that are specially designed for improving the conductivity of the electrical components.
• If the P0122 code is still appearing, the sensor itself could be malfunctioning. You can check whether it works by measuring its voltage with a digital multimeter. Install a new one if this value is too low.