Vacuum Sensor

The vacuum sensor measures changes in manifold pressure (vacuum). Changes in manifold pressure can result from engine load and speed changes. The vacuum sensor converts these changes in manifold pressure into a voltage output signal to the ECM. The ECM can monitor these signals and adjust air/fuel ratio and ignition timing accordingly.

The vacuum sensor also measures the difference between atmospheric pressure (outside air) and manifold pressure (vacuum). A problem in the vacuum sensor circuit may set a Code "34".