The TPS (Throttle Position Sensor) calculates the amount of throttle entry. As the throttle opens, the reading in volts increases. This sensor receives 5 volts from the PCM (Powertrain Control Module) corresponding to the reference signal. It also receives a ground.
Normally, during idle the voltage is 0.5, while the maximum acceleration is 4.5 volts. If the PCM finds that the angle of the throttle is less or greater than necessary for the specific RPM, DTC code P0221 OBDII will be established. This code indicates sector B of the circuit.