The barometric pressure (BARO) sensor measures the pressure of the atmosphere. This pressure is affected by altitude and weather conditions. A diaphragm within the BARO sensor is displaced by the pressure changes that occur from varying altitudes and weather conditions. The sensor translates this diaphragm action into the voltage signal input that is used by the engine control module (ECM) for diagnostics, emissions control, and to calculate fuel delivery.

Changes in BARO due to weather are relatively small, while changes due to altitude are significant. Pressure can range from 56 kPa at an altitude of 4 267 meters (14,000 feet), to 104 kPa at or below sea level. The BARO sensor has a 5V reference circuit, a low reference circuit and a signal circuit. The BARO sensor provides a voltage signal to the ECM on a signal circuit relative to barometric pressure changes.

The ECM detects that 80 out of 100 consecutive BARO sensor samples vary greater than 10 kPa between each sample, for 10 seconds.

DTC P2227 is a Type B DTC.

DTC P2227 is a Type B DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 35555 Metal Mityvac

1. Ignition ON, observe the scan tool MAP, SC Inlet Pressure, and BARO sensor parameters. The readings should be within 5 kPa of each other and also the current BARO for your location. Refer to Altitude Versus Barometric Pressure.
2. Operate the vehicle within the Conditions for Running the DTC to verify that the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Engine running, monitor the BARO parameter with the scan tool for a steady value.

Note: You must perform the Circuit/System Testing before proceeding with the Component Test.

1. Ignition ON, engine OFF, remove the BARO sensor.
2. Install a 3A fused jumper wire between the 5V reference terminal 1 of the sensor and 5V reference.
3. Install a jumper wire between the low reference terminal 2 of the sensor and ground.
4. Install a jumper wire at the signal terminal 3 of the BARO sensor.
5. Connect a DMM between the jumper wire from terminal 3 of the sensor and ground.
6. Install the J 35555 Metal Mityvac to the BARO sensor vacuum port. Slowly apply vacuum to the sensor while monitoring the voltage on the DMM. The voltage should vary between 5.2-0V, without any spikes or dropouts.

⇒	If the voltage is not within the specified range or is erratic, replace the BARO sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.