For 1990-2009 cars

### Description

The DTC P1450 Barometric Pressure (BARO) Sensor Circuit diagnostic monitors the BARO sensor output. The BARO sensor and circuitry are located inside of the powertrain control module (PCM). Barometric pressure varies with weather conditions and changes in the altitude from sea level. The PCM modifies fuel and spark delivery in response to barometric pressure changes.

### Conditions for Running the DTC

The engine is running.

### Conditions for Setting the DTC

The BARO is less than 38 kPa for more than 5 seconds.

OR:

The BARO is more than or equal to 113 kPa for more than 5 seconds.

### Action Taken When the DTC Sets

• | The PCM illuminates the malfunction indicator lamp (MIL).

• | The PCM records the operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame buffer.

• | The PCM enters the Failsafe mode and operates as if the barometric pressure is 101 kPa (760 mm Hg).

### Conditions for Clearing the MIL/DTC

• | The MIL turns OFF after 3 consecutively passing trips without a fault present.

• | A history DTC clears after 40 consecutive warm-up cycles without a fault.

• | Perform the scan tool Clear DTC Information function.

### Diagnostic Aids

Barometric pressure varies depending on weather conditions and altitude. Typical barometric pressure at sea level is 100 kPa (29-30 in Hg).

If DTC P1450 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC was first set.

### Test Description

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

1. The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

2. This step checks that the BARO sensor is reading atmospheric pressure. Normal atmospheric pressure will be near 100 kPa at sea level.

3. This step checks that the MAP sensor reading and the BARO sensor reading are almost equal. When the engine is not running intake manifold pressure and atmospheric pressure should be the same, therefore both sensors should indicate approximately the same pressure. Normal atmospheric pressure will be near 100 kPa at sea level. When the engine is not running intake manifold pressure and atmospheric pressure should be the same.

4. Clearing the DTCs by removing the DOME fuse also clears the PCM long term memory. Using the scan tool to clear DTCs leaves the long term memory active. DTC emitting diagnostics may not run to completion as expected unless the long term memory is cleared. Removal of the DOME fuse also clears the time display of the radio.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics
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. Install a scan tool.
3. Observe the BARO parameter on the scan tool.

Is the BARO pressure indicated near the specified value?

97-100 kPa

Go to Step 4

Go to Step 3

3 |

1. Turn ON the ignition, leaving the engine OFF.
2. Clear the scan tool information.
3. Compare the pressure readings of the BARO sensor and the MAP sensor on the scan tool.

Is the difference between the BARO pressure and the MAP pressure more than the specified value?

3 kPa

Go to Step 5

Go to Step 4

4 |

1. Turn ON the ignition, leaving the engine OFF.
2. Clear the scan tool information.
3. Operate the vehicle within the Freeze Frame conditions as specified.

Is DTC P1450 set?

--

Go to Step 5

Go to Diagnostic Aids

5 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 6 | --
6 |

1. Turn OFF the ignition.
2. Remove the DOME fuse for 30 seconds.
3. Install the DOME fuse.
4. Reset the radio clock time. Refer to Radio/Audio System Description and Operation in Entertainment.
5. Start the engine.
6. Operate the vehicle within the Freeze Frame conditions as specified.

Does the DTC run and pass?

--

Go to Step 7

Go to Step 2

7 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List | System OK