DTC P0121: TP Sensor Performance: Description

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 Pontiac Grand Prix, 2002 Pontiac Bonneville, 2002 Chevrolet Monte Carlo, 2002 Chevrolet Impala, and 2002 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.

Throttle Position (TP) sensor is used by Powertrain Control Module (PCM) to determine throttle plate angle for various engine management systems. TP sensor is a potentiometer type sensor with 3 circuits: a 5-volt reference circuit, a low reference circuit, and a signal circuit. PCM provides TP sensor with a 5-volt reference circuit and a low reference circuit. Rotation of TP sensor rotor from closed throttle position to Wide Open Throttle (WOT) position provides PCM with a signal voltage from less than one volt to more than 4 volts through TP sensor signal circuit. PCM will use Manifold Absolute Pressure (MAP) sensor to determine if predicted operating range of TP sensor is correct. A skewed MAP sensor may cause this DTC to set and should be tested for proper operation if TP sensor is determined to be operating properly and this DTC continues to set.