GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2008 🢒 LaCrosse 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P2227, P2228, or P2229

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    •  Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P2227: Barometric Pressure (BARO) Sensor Performance

DTC P2228: Barometric Pressure (BARO) Sensor Circuit Low Voltage

DTC P2229: Barometric Pressure (BARO) Sensor Circuit High Voltage

Circuit/System Description

The barometric pressure (BARO) sensor responds to changes in altitude and atmospheric conditions. This gives the engine control module (ECM) an indication of BARO. The ECM uses this information to calculate fuel delivery. The BARO sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The 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 the atmospheric pressure changes. The ECM monitors the BARO sensor signal for a voltage outside of the normal range.

Conditions for Running the DTC

P2227

    • Before the ECM can report DTC P2227 failed, DTCs P0101, P0102, P0103, P0121, P0122, P0123, P0221, P0222, P0223, P2228, and P2229 must run and pass.
    • The engine is operating for greater than 20 seconds.
    • The mass air flow is greater than 11 g/s.
    • The evaporative emissions (EVAP) leak test is not active.
    • The difference between the calculated manifold absolute pressure (MAP) and BARO pressure is less than 1.0 kPa for greater than 3 seconds.
    • DTC P2227 runs continuously once the above conditions are met for 2 seconds.

P2228 or P2229

    • The engine is operating.
    • The DTCs run continuously once the above conditions are met for 2 seconds.

Conditions for Setting the DTC

P2227

    • The ECM detects that the BARO pressure is less than 43 kPa or greater than 115 kPa.
    • The ECM detects that the BARO pressure changed greater than 5 kPa within 20 seconds.
    • The ECM detects that the BARO pressure changed greater than 30 kPa since the last ignition cycle.
    • Any of the condition above exist for 4 seconds or for a cumulative of 50 seconds.

P2228

    • The ECM detects that the BARO sensor voltage is less than 0.20 volts and the BARO pressure is less than 50 kPa.
    • The conditions are met for greater than 4 seconds or for a cumulative of 50 seconds.

P2229

    • The ECM detects that the BARO sensor voltage is greater than 4.87 volts and the BARO pressure is greater than 115 kPa.
    • The conditions are met for greater than 4 seconds or for a cumulative of 50 seconds.

Action Taken When the DTC Sets

DTCs P2227, P2228, and P2229 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P2227, P2228, and P2229 are Type B DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Start the engine. Observe the scan tool DTC information. DTCs P2227, P2228, or P2229 should not set.
  2. 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 are captured in the Freeze Frame/Failure Records Data List.

Circuit/System Testing
  1. Ignition OFF, remove the fuse that supplies B+ to terminal X2-36 of the ECM.
  2. Disconnect the harness connector at the BARO sensor.
  3. Test for less than 5 ohms of resistance between the low reference circuit terminal 2 and ground.
    4. ⇒If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  4. Install the fuse that supplies B+ to terminal X2-36 of the ECM.
  5. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 1 and ground.
    6. ⇒If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. 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.
  6. Test for 5.2-6.2 volts between the signal circuit terminal 3 and ground.
    7. ⇒If less than the specified range, test the signal circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the ECM.
    ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  7. If all circuits test normal, replace the BARO sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for engine control module replacement, setup, and programming