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 Sensor: Description and Operation

Barometric Pressure Sensor:






PURPOSE
The Engine Control Module (ECM) uses the voltage signal to adjust the air-fuel ratio and ignition timing as altitude changes to improve driveability at high altitude.

OPERATION
- The ECM supplies a 5 Volt reference and a ground to the sensor.
- As the resistance of the sensor changes the voltage across the sensor varies. This voltage is read as barometric pressure by the ECM.