Throttle/Pedal Position Sensor/Switch “A” Circuit Low Input

Our emissions expert has put together the following information about the P0122 fault code. We have also included diagnostic procedures you can take to your repair shop if the mechanic is having difficulty analyzing the code.

OBD II Fault Code

OBD II P0122

Fault Code Definition
Code P0122 is triggered when the voltage output from the Throttle/Pedal Position Sensor/Switch to the PCM is too low.

The Throttle Position Sensor/Switch is located on the Throttle Body of the Intake Manifold and the Pedal Position Sensor/Switch is located on the Accelerator Pedal. These sensors provide precise input from the driver’s foot in terms of how much power is needed—and how urgently—from the engine.

As the Throttle Position Sensor is rotated from its base resting position to full acceleration, it sends a increasing voltage signal to the Powertrain Control Module (PCM). This decreasing or increasing voltage signal is used by the PCM to manage the Air Fuel Ratio and Spark Timing of the engine as well as other emissions system components.

Symptoms

Check Engine Light will illuminate
In many cases, no abnormal symptoms may be noticed
In some cases, the engine may be hard starting
In some cases, the engine may hesitate during acceleration
Common Problems That Trigger the P0122 Code

Defective Throttle Position Sensor or Switch
Torn or jammed floor mats
Faulty or corroded Throttle/Pedal Position Sensor/Switch wiring or connections
Common Misdiagnoses

Throttle or Pedal Position Sensor is replaced when the real problem is a poor connection or chafed wiring
Pedal Position Sensor is replaced when the real problem is torn or damaged floor mats

Possible Solutions

Some recommended troubleshooting and repair steps are:

Carefully check the throttle position sensor (TPS), wiring connector, and wiring for breaks, etc. Repair or replace as necessary
Check the voltage at the TPS (refer to a service manual for your vehicle for specific information). If the voltage is too low that is indicative of a problem. Replace if necessary.
If recently replaced the TPS may need to be adjusted. On some vehicles the installation instructions call for the TPS to be properly aligned or adjusted, consult a repair manual for specifics.
If there are no symptoms at all, the problem may be intermittent and clearing the code may resolve the issue temporarily. If this is the case then you should definitely check the wiring to be sure it’s not rubbing on anything, grounding, etc. The code may come back.
Other TPS sensor and circuit related DTCs: P0120, P0121, P0123, P0124