P2229

DESCRIPTION
The DTC P2229 Barometric Pressure (BARO) Sensor Circuit High Voltage 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 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 Fail-safe 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 P2229 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

Steps 1-5:

Steps 6-9:

The numbers below refer to the step numbers in the diagnostic table.
1. The Diagnostic System Check-Computers and Control Systems 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. The mass air flow (MAF) sensor, knock sensor (KS), and BARO sensor all share the same 5-volt reference supply. If the 5-volt circuit is pulled low, the BARO sensor will be 126 kPa and a DTC P2229 will set.
3. This step checks that the BARO sensor is reading atmospheric pressure. Normal atmospheric pressure will be near 100 kPa at sea level.
4. This step checks that the manifold absolute pressure (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.
6. The 5-volt reference circuit of the TP sensor C1-1, the MAP sensor C2-14, and the FTP sensor C2-13 are all tied internally within the PCM.
8. 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.