GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2006 🢒 Grand Prix 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 DTC P2227, P2228, or P2229

DTC Descriptors (L32 ONLY)

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

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

5-Volt Reference Circuit

P0069, P0651, P2228, P0530, P0463

P0069

P0069, P2228

P0069

--

Sensor Signal Circuit

P0069, P2228

P0069

P0069, P2228

P0069

--

Low Reference Circuit

--

P0069

P0069, P2229

--

--

Typical Scan Tool Data

BARO Sensor

Circuit

Normal Range

Short to Ground

Open

Short to Voltage

5-Volt Reference Circuit

--

8 kPa

8 kPa

200 kPa

Sensor Signal Circuit

Refer to Altitude Versus Barometric Pressure

8 kPa

8 kPa

200 kPa

Low Reference Circuit

--

--

191 kPa

--

Circuit/System Description

The barometric pressure (BARO) sensor is a transducer that varies resistance according to changes in altitude and atmospheric conditions. This gives the control module an indication the current of barometric pressure. The control module 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 control module 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 control module on a signal circuit relative to the pressure changes.

P2227

The control module monitors the stability of the BARO sensor output by comparing successive samples. If the control module detects that the difference between the samples is more than a predetermined amount, DTC P2227 sets.

P2228

The control module monitors the BARO sensor signal for voltage outside of the normal range. If the control module detects a BARO sensor signal voltage that is excessively low, DTC P2228 sets.

P2229

The control module monitors the BARO sensor signal for voltage outside of the normal range. If the control module detects a BARO sensor signal voltage that is excessively high, DTC P2229 sets.

Conditions for Running the DTC

P2227

    • DTCs P0068, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0125, P0128, P0220, P0502, P0503, P2135, P2228, P2229 are not set.
    • The engine run time is more than 10 seconds.

P2228 or P2229

The ignition is ON.

Conditions for Setting the DTC

P2227

    • The control module detects that 80 out of 100 consecutive BARO sensor samples vary more than 10 kPa between each sample.
    • The above condition is met for 10 seconds.

P2228

The control module detects that the BARO is less than 18 kPa for 10 seconds.

P2229

The control module detects that the BARO sensor pressure is more than 176 kPa for 10 seconds.

Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Powertrain Control Module Connector End Views
    •  Engine Controls Connector End Views

Electrical Information Reference

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

Special Tools Required

J 23738-A Mityvac Vacuum Pump

Circuit/System Testing

Always perform the Diagnostic System Check - Vehicle.

P2227

Start the vehicle and monitor the BARO parameter with the scan tool for rapid fluctuation during any part of operation.

⇒If the BARO parameter DOES NOT fluctuates rapidly then, refer to Inducing Intermittent Fault Conditions .
⇒If the BARO parameter fluctuates rapidly.
    • Test for an intermittent and for a poor connection at the BARO sensor.
    • Test all of the BARO sensor circuits for intermittent shorts or opens.
    • Test for an intermittent and for a poor connection at the control module.

P2228

  1. Observe the DTC information with a scan tool. If P0651 is set, then diagnose it first.
  2. Turn ON the ignition, with the engine OFF.
  3. Observe the BARO sensor with a scan tool for 18 kPa.
    4. ⇒If less than 18 kPa, then test for an intermittent and for poor connection at the BARO sensor.
  4. Disconnect the BARO sensor electrical connector.
  5. Measure for 4.8 volts from the 5-volt reference circuit of the BARO sensor to a good ground.
    6. ⇒If less than 4.8 volts, then test the 5-volt reference circuit of the BARO sensor for an open.
  6. Connect a 3-amp fused jumper wire between the 5-volt reference circuit of the BARO sensor and the signal circuit of the BARO sensor.
  7. Observe the BARO parameter for 198 kPa with a scan tool.
    8. ⇒If more than 198 kPa, then replace the BARO sensor.
    ⇒If less than 198 kPa, then test the signal circuit of the BARO sensor for an open, a short to ground or an intermittent or poor connection at the control module. If the circuit tests normal, replace the control module.

P2229

  1. Observe the DTC information with a scan tool. If P0651 is set, then diagnose it first.
  2. Start the engine.
  3. Observe the BARO sensor parameter for 176 kPa with a scan tool.
    4. ⇒If less than 176 kPa, refer to Testing for Intermittent Conditions and Poor Connections .
  4. Turn ON the ignition, with the engine OFF.
  5. Disconnect the BARO sensor electrical connector.
  6. Observe the BARO sensor parameter for 10 kPa with a scan tool.
    7. ⇒If more than 10 kPa, then test the BARO sensor signal circuit between the control module and the BARO sensor for a short to voltage.
  7. Turn OFF the ignition.
  8. Connect a jumper wire between each of the terminals in the BARO sensor harness connector and the corresponding terminal at the BARO sensor.
  9. Turn ON the ignition with the engine OFF.
  10. Measure for 0.2 volt from the low reference circuit of the BARO sensor at the jumper wire terminal to a good ground with a DMM.
    11. ⇒If more than 0.2 volt than, test the low reference circuit between the control module and BARO sensor for high resistance or for an open, or for an intermittent and for a poor connection at the control module. If the circuit tests normal, replace the control module.
    ⇒If less than 0.2 volt than, test for an intermittent and for a poor connection at the BARO sensor. If all the circuit tests normal, replace the BARO sensor.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Control Module References
    •  Barometric Pressure Sensor Replacement

Repair Verification

Diagnostic Repair Verification