The barometric pressure sensor (BARO) 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 the 5-volt reference 2 circuit, and provides a ground on a low reference circuit. The BARO sensor provides a signal to the ECM on a signal circuit relative to the pressure changes. The ECM compares the BARO sensor to the boost sensor in order to monitor the BARO sensor operation. This DTC will set if the difference between the two sensors is more than a predetermined amount.
• | DTCs P0101, P0102, P0103, P0107, P0108, P0116, P0117, P0118, P0236, P0237, P0238, P0335, P0336, or P0500 is not set. |
• | The engine speed is between 500-900 RPM. |
• | The engine run time is more than 20 seconds. |
• | The accelerator pedal angle is less than 20 percent. |
• | The vehicle speed is less than 40 km/h (25 mph). |
• | The mass air flow (MAF) is less than 50 g/s. |
• | The engine coolant temperature (ECT) is more than 80°C (176°F). |
• | The power take off (PTO) is OFF. |
• | The above conditions exist for 5 seconds. |
The difference between the BARO sensor and the boost sensor is more than 20 kPa for 2 seconds.
• | 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. |
• | 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. |
• | Use a scan tool in order to clear the DTC. |
• | Inspect for any condition that would cause the ECM to receive a false BARO reading including the following: |
- | A skewed boost sensor |
- | A skewed BARO sensor |
- | High circuit resistance, inspect for the following conditions: |
• | Rubbed wire insulation |
• | Wire corrosion |
• | Terminal corrosion |
• | If an intermittent condition exists, refer to Intermittent Conditions . |
The numbers below refer to the step numbers on the diagnostic table.
This step tests the BARO sensors ability to correctly indicate barometric pressure. The value shown for the BARO sensor varies with altitude.
This step tests for a sensor stuck in range.
Step | Action | Values | Yes | No | ||||||
---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||
2 |
Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 3 | ||||||
Important: The vehicle used for a comparison is not limited to the same type of vehicle that is being serviced. A vehicle known to provide an accurate BARO reading is acceptable.
Is the pressure difference between the vehicles less than the specified value? | 5 kPa | Go to Step 4 | Go to Step 6 | |||||||
Does the scan tool indicate that the BARO sensor pressure decreases smoothly through the test? | -- | Go to Step 5 | Go to Step 6 | |||||||
5 | Disconnect the hand vacuum pump from the BARO sensor port. Does the BARO sensor pressure return to the original value that was observed in step 3? | -- | Go to Diagnostic Aids | Go to Step 18 | ||||||
6 |
Does the scan tool indicate that the BARO sensor pressure is more than the specified value? | 44 kPa | Go to Step 15 | Go to Step 7 | ||||||
7 |
Does the voltage measure more than the specified value? | 4.4 V | Go to Step 8 | Go to Step 14 | ||||||
8 | Does the voltage measure more than the specified value? | 5.2 V | Go to Step 11 | Go to Step 9 | ||||||
9 | 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. Does the scan tool indicate the BARO sensor pressure is more than the specified value? | 200 kPa | Go to Step 10 | Go to Step 13 | ||||||
10 |
Does the test lamp illuminate? | -- | Go to Step 16 | Go to Step 12 | ||||||
11 | Test the 5-volt reference circuit of the BARO sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 19 | ||||||
12 | Test the low reference circuit of the BARO sensor for high resistance or an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 17 | ||||||
13 |
Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 17 | ||||||
14 |
Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 17 | ||||||
15 | Test the signal circuit of the BARO sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 19 | ||||||
16 | Inspect the BARO sensor for poor connections. 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 20 | Go to Step 18 | ||||||
17 | Inspect the ECM for poor connections. 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 20 | Go to Step 19 | ||||||
18 | Replace the BARO sensor. Refer to Barometric Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||
19 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- | ||||||
20 |
Does the DTC run and pass? | -- | Go to Step 21 | Go to Step 2 | ||||||
21 | Observe the stored information in Capture Info. with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |
The barometric pressure sensor (BARO) 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 the 5-volt reference 2 circuit, and provides a ground on a low reference circuit. The BARO sensor provides a signal to the ECM on a signal circuit relative to the pressure changes. The ECM compares the BARO sensor to the exhaust gas recirculation (EGR) vacuum sensor in order to monitor the BARO sensor operation. This DTC will set if the difference between the 2 sensors is more than a predetermined amount.
• | DTCs P0101, P0102, P0103, P0107, P0108, P0116, P0117, P0118, P0236, P0237, P0238, P0335, P0336, P0404, P0405, P0406, or P0500 is not set. |
• | The engine speed is between 500-3,600 RPM. |
• | The engine run time is more than 8 seconds. |
• | The vehicle speed is less than 161 km/h (100 mph). |
• | The mass air flow (MAF) is less than 444 g/s. |
• | The engine coolant temperature (ECT) is more than 20°C (68°F). |
• | The power take off (PTO) is OFF. |
• | The above conditions exist for 5 seconds. |
The difference between the BARO sensor and the EGR vacuum sensor when the EGR is inactive is more than 10 kPa for 6 seconds.
• | The control module illuminated 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. |
• | 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. |
• | Use a scan tool in order to clear the DTC. |
• | Inspect for any condition that would cause the ECM to receive a false BARO reading including the following: |
- | A skewed EGR vacuum sensor |
- | A skewed BARO sensor |
- | High circuit resistance, inspect for the following conditions: |
• | Rubbed wire insulation |
• | Wire corrosion |
• | Terminal corrosion |
• | If an intermittent condition exists, refer to Intermittent Conditions . |
The numbers below refer to the step numbers on the diagnostic table.
This step tests the BARO sensors ability to correctly indicate barometric pressure. The value shown for the BARO sensor varies with altitude.
The EGR system will activate at idle when the coolant temperature is more than 60°C (140°F). The EGR system must be disabled for this step.
This step tests for a sensor stuck in range.
Step | Action | Values | Yes | No | ||||||
---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||
2 |
Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 3 | ||||||
Is the difference between the sensors more than the specified value? | 10 kPa | Go to Step 7 | Go to Step 4 | |||||||
Is the difference between the sensors more than the specified value? | 10 kPa | Go to Step 12 | Go to Step 5 | |||||||
Does the BARO sensor pressure decreases smoothly through the test? | -- | Go to Step 6 | Go to Step 7 | |||||||
6 | Disconnect the hand vacuum pump from the BARO sensor port. Does the BARO sensor pressure return to the original value that was observed in step 3? | -- | Go to Diagnostic Aids | Go to Step 20 | ||||||
7 |
Does the BARO sensor pressure measure more than the specified value? | 44 kPa | Go to Step 17 | Go to Step 8 | ||||||
8 |
Does the voltage measure more than the specified value? | 4.4 V | Go to Step 9 | Go to Step 16 | ||||||
9 | Does the voltage measure more than the specified value? | 5.2 V | Go to Step 13 | Go to Step 10 | ||||||
10 | 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. Does the BARO sensor pressure measure more than the specified value? | 110 kPa | Go to Step 11 | Go to Step 15 | ||||||
11 |
Does the test lamp illuminate? | -- | Go to Step 18 | Go to Step 14 | ||||||
12 |
Did you complete the repair? | -- | Go to Step 22 | -- | ||||||
13 | Test the 5-volt reference circuit of the BARO sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 21 | ||||||
14 | Test the low reference circuit of the BARO sensor for high resistance or an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 19 | ||||||
15 |
Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 19 | ||||||
16 |
Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 19 | ||||||
17 | Test the signal circuit of the BARO sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 22 | Go to Step 21 | ||||||
18 | Inspect the BARO sensor for poor connections. 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 22 | Go to Step 20 | ||||||
19 | Inspect the ECM for poor connections. 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 22 | Go to Step 21 | ||||||
20 | Replace the BARO sensor. Refer to Barometric Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 22 | -- | ||||||
21 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 22 | -- | ||||||
22 |
Does the DTC run and pass? | -- | Go to Step 23 | Go to Step 2 | ||||||
23 | Observe the stored information in Capture Info, with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |