Circuit Description

WARNING: This page is about a different car, the 2004 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

The barometric pressure (BARO) sensor is a transducer that varies resistance according to changes in altitude and atmospheric conditions. This gives the powertrain control module (PCM) an indication of the current barometric pressure. The PCM uses this information to calculate fuel delivery. The BARO sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The PCM supplies 5 volts to the BARO sensor on a 5-volt reference circuit, and provides a ground on a low reference circuit. The BARO sensor provides a voltage signal to the PCM on a signal circuit relative to the pressure changes. The PCM monitors the stability of the BARO sensor output by comparing successive samples. If the PCM detects that the difference between the samples is more than a predetermined amount, DTC P2227 sets.