The barometric pressure (BARO) sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The engine control module (ECM) 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 ECM on a signal circuit relative to barometric pressure changes.

P2228--Key On Test

P2228--Engine Running Test

P2229

P2228

The BARO is less than 8 kPa for less than 1 minute.

P2229

The BARO is greater than 199 kPa for less than 1 minute.

DTCs P2228 and P2229 are Type B DTCs.

DTCs P2228 and P2229 are Type B DTCs.

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. Verify that the following DTCs are not set: P0641 or P0651.

⇒	If any of the DTCs are set, refer to DTC P0641 or P0651.

2. Ignition ON, observe the BARO parameter with a scan tool. The BARO parameter should be within the range specified in the altitude vs. barometric pressure table. Refer to Altitude Versus Barometric Pressure.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Ignition OFF, disconnect the harness connector at the BARO sensor.
2. Ignition OFF for 90 seconds, test for less than 5 ohms of resistance between the low reference circuit terminal A of the connector and a good ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal C and ground.

⇒	If less than the specified range, test the 5-volt reference circuit for an open/high resistance or a short to ground. If the circuit tests normal, replace the ECM.

⇒	If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. Verify the scan tool BARO sensor voltage parameter is less than 15 kPa.

⇒	If greater than the specified range, tests the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

5. Install a 3A fused jumper wire between the signal circuit terminal B and the 5-volt reference circuit terminal C. Verify the scan tool BARO sensor parameter is greater than 190 kPa.

⇒	If less than the specified range, test the sensor signal circuit for an open/high resistance or a short to ground.

6. If all circuits test normal, test or replace the BARO sensor.

Important: 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 5-volt reference terminal C of the sensor and 5-volt reference.
3. Install a jumper wire between the low reference terminal A of the sensor and ground.
4. Install a jumper wire at the signal terminal B of the BARO sensor.
5. Connect a DMM between the jumper wire from terminal B of the sensor and ground.
6. Install the J 35555 to the BARO sensor vacuum port. Slowly apply vacuum to the sensor while monitoring the voltage on the DMM. The voltage should vary between 5.2-0 volts, 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.