GM Service Manual Online
For 1990-2009 cars only

DTC P2229 Federal RPO FE9, NG1

Circuit Description

The barometric pressure (BARO) sensor responds to changes in altitude and atmospheric conditions. This gives the engine control module (ECM) an indication of barometric pressure. 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 pressure changes. The ECM monitors the BARO sensor signal for voltage outside of the normal range. If the ECM detects a BARO sensor signal voltage that is excessively high, this DTC will set.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The BARO is more than 110 kPa for 2 seconds.

Action Taken When the DTC Sets

    • The control module stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
    • The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC

    • 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 non-emission related diagnostic.
    • Clear the DTC with a scan tool.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. A short to voltage on the 5-volt reference circuit will cause DTC P0651 to set.

  2. This step tests the signal circuit of the BARO sensor for a short to voltage. The short may backfeed through the sensor to the 5-volt reference circuit causing DTC P0651 to set.

  3. This step tests the signal circuit of the boost sensor for a short to voltage. The short may backfeed through the sensor to the 5-volt reference circuit causing DTC P0651 to set.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Turn ON the ignition, with the engine OFF.
  2. Observe the BARO sensor pressure with a scan tool.

Does the scan tool indicate that the pressure is more than the specified value?

110 kPa

Go to Step 4

Go to Step 3

3

  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 4

Go to Intermittent Conditions

4

Monitor the Diagnostic Trouble Code (DTC) Information with a scan tool.

Does the scan tool indicate that DTC P0651 is current?

--

Go to Step 7

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Disconnect the electrical connector of the BARO sensor. Refer to Barometric Pressure Sensor Replacement .
  3. Turn ON the ignition, with the engine OFF.

Does the scan tool indicate that the BARO sensor pressure is less than the specified value?

44 kPa

Go to Step 6

Go to Step 9

6

  1. Turn OFF the ignition.
  2. Connect a jumper wire between each of the terminals in the BARO sensor harness connector and the corresponding terminal at the BARO sensor. Refer to Using Connector Test Adapters in Wiring Systems.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the low reference circuit of the BARO sensor at the jumper wire terminal to a good ground with a DMM. Refer to Measuring Voltage Drop in Wiring Systems.

Is the voltage more than the specified value?

0.2 V

Go to Step 11

Go to Step 12

7

  1. Turn OFF the ignition.
  2. Disconnect the electrical connector of the BARO sensor. Refer to Barometric Pressure Sensor Replacement .
  3. Turn ON the ignition, with the engine OFF.

Does the scan tool indicate that the BARO sensor pressure is less than the specified value?

44 kPa

Go to Step 8

Go to Step 9

8

Disconnect the electrical connector of the boost sensor. Refer to Boost Sensor Replacement .

Does the scan tool indicate that the boost sensor pressure is less than the specified value?

50 kPa

Go to DTC P0651

Go to Step 10

9

Test the signal circuit of the BARO sensor for a short to voltage. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 15

10

Test the signal circuit of the Boost sensor for a short to voltage. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 15

11

Test the low reference circuit of the BARO sensor for high resistance or an open. Refer to Circuit Testing in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

12

Inspect for poor connections at the BARO sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 14

13

Inspect for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 15

14

Replace the BARO sensor. Refer to Barometric Pressure Sensor Replacement .

Did you complete the replacement?

--

Go to Step 16

--

15

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

--

Go to Step 16

--

16

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 17

17

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK

DTC P2229 California RPO YF5, NE1, and VCL

Circuit Description

The barometric pressure (BARO) sensor responds to changes in altitude and atmospheric conditions. This gives the engine control module (ECM) an indication of barometric pressure. 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 pressure changes. The ECM monitors the BARO sensor signal for voltage outside of the normal range. If the ECM detects a BARO sensor signal voltage that is excessively high, this DTC will set.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

The BARO is more than 110 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.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. A short to voltage on the 5-volt reference circuit will cause DTC P0651 to set.

  2. This step tests the signal circuit of the BARO sensor for a short to voltage. The short may backfeed through the sensor to the 5- volt reference circuit causing DTC P0651 to set.

  3. This step tests the signal circuit of the boost sensor for a short to voltage. The short may backfeed through the sensor to the 5-volt reference circuit causing DTC P0651 to set.

  4. This step tests the signal circuit of the EGR vacuum sensor for a short to voltage. The short may backfeed through the sensor to the 5-volt reference circuit causing DTC P0651 to set.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Turn ON the ignition, with the engine OFF.
  2. Observe the BARO sensor pressure with a scan tool.

Does the scan tool indicate that the pressure is more than the specified value?

110 kPa

Go to Step 4

Go to Step 3

3

  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 4

Go to Intermittent Conditions

4

Monitor the Diagnostic Trouble Code (DTC) Information with a scan tool.

Does the scan tool indicate that DTC P0651 is current?

--

Go to Step 7

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Disconnect the electrical connector of the BARO sensor. Refer to Barometric Pressure Sensor Replacement .
  3. Turn ON the ignition, with the engine OFF.

Does the scan tool indicate that the BARO sensor pressure is less than the specified value?

14 kPa

Go to Step 6

Go to Step 10

6

  1. Turn OFF the ignition.
  2. Connect a jumper wire between each of the terminals in the BARO sensor harness connector and the corresponding terminal at the BARO sensor. Refer to Using Connector Test Adapters in Wiring Systems.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the low reference circuit of the BARO sensor at the jumper wire terminal to a good ground with a DMM. Refer to Measuring Voltage Drop in Wiring Systems.

Is the voltage more than the specified value?

0.2 V

Go to Step 14

Go to Step 15

7

  1. Turn OFF the ignition.
  2. Disconnect the electrical connector of the BARO sensor. Refer to Barometric Pressure Sensor Replacement .
  3. Turn ON the ignition, with the engine OFF.

Does the scan tool indicate that the BARO sensor pressure is less than the specified value?

44 kPa

Go to Step 8

Go to Step 11

8

Disconnect the electrical connector of the boost sensor. Refer to Boost Sensor Replacement .

Does the scan tool indicate that the boost sensor pressure is less than the specified value?

50 kPa

Go to Step 9

Go to Step 12

9

Disconnect the electrical connector of the EGR vacuum sensor. Refer to Exhaust Gas Recirculation Valve Vacuum Sensor Replacement .

Does the scan tool indicate that the EGR vacuum sensor pressure is less than the specified value?

18 kPa

Go to DTC P0651

Go to Step 13

10

Test the signal circuit of the BARO sensor for a short to 5 volts. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 18

11

Test the signal circuit of the BARO sensor for a short to battery voltage. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 18

12

Test the signal circuit of the Boost sensor for a short to battery voltage. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 18

13

Test the signal circuit of the EGR vacuum sensor for a short to battery voltage. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 18

14

Test the low reference circuit of the BARO sensor for high resistance or an open. Refer to Circuit Testing in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 16

15

Inspect for poor connections at the BARO sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 17

16

Inspect for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 18

17

Replace the BARO sensor. Refer to Barometric Pressure Sensor Replacement .

Did you complete the replacement?

--

Go to Step 19

--

18

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

--

Go to Step 19

--

19

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 20

20

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK