The DTC P2228 Barometric Pressure (BARO) Sensor Circuit diagnostic monitors the BARO sensor output. The barometric pressure (BARO) sensor and circuitry are located inside of the powertrain control module (PCM). The PCM uses the barometric pressure information in order to compensate for altitude changes. The BARO sensor reading is displayed on a scan tool when the ignition switch is ON and the engine is OFF.

The engine is running.

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

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

If the DTC P2228 is intermittent, driving the vehicle under the following conditions can verify whether the fault is present. Perform the scan tool Clear DTC Information function. Road test the vehicle while monitoring the DTC P2228 diagnostic on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If DTC P2228 appears in the Not Ran Since Code Cleared list, the P2228 diagnostic has not yet run. When DTC P2228 does not appear in the Not Ran Since Code Cleared list, the P2228 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the P2228 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status in order to determine the outcome of the diagnostic test involved.

If DTC P2228 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.

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 determines if a fault is present.

3. This step checks for a short to ground in the PCM 5-volt reference circuit. The BARO sensor shares the 5-volt reference supply from the PCM with the MAP sensor, the TP sensor, and the fuel tank pressure sensor. A short in any branch of the reference voltage circuit will cause a DTC P2228 to set.

5. The DTC P2228 diagnostic can be monitored on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC P2228 appears in the Not Ran Since Code Cleared list, the DTC P2228 diagnostic has not yet run. When the DTC P2228 does not appear in the Not Ran Since Code Cleared list, the DTC P2228 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the DTC P2228 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status, in order to determine the outcome of the diagnostic test involved.