Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Barometric Pressure Switch: Description and Operation

Barometric Pressure Sensor Circuit:





The Barometric Pressure Sensor, located in the Air Flow Sensor (AFS), senses the atmospheric pressure and converts it into a Voltage which is sent to the ECU. The ECU uses this signal to compute the altitude at which the vehicle is running, accordingly correcting the air-fuel ratio and the ignition timing, thus improving driveability at high altitude.