DTC P0121: TP Sensor Performance: Description

WARNING: This page is about a different car, the 2002 Pontiac Firebird and 2002 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.

The Throttle Position (TP) sensor is used by the Powertrain Control Module (PCM) to determine the throttle plate angle for various engine management systems. The TP sensor is potentiometer sensor with a 5-volt reference circuit, a low reference circuit, and a signal circuit. The PCM provides the TP sensor with a 5-volt reference circuit and a low reference circuit. Rotation of the TP sensor from the closed throttle position to the Wide Open Throttle (WOT) position provides the PCM with a signal voltage from less than 1 volt to more than 4 volts through the TP sensor signal circuit. When the Conditions for Running this DTC are met, the PCM will use the Manifold Absolute Pressure (MAP) sensor in order to determine if the predicted operating range of the TP sensor is correct. When the TP sensor voltage is out of this predicted range, DTC P0121 sets.