Federal RPO FE9, NG1

DTC P2227 (FEDERAL WITH RPO CODE 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 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.

CONDITIONS FOR RUNNING THE DTC
- DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0236, P0237, P0238, P0335, P0336, P0500, P2228, P2229 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.

CONDITIONS FOR SETTING THE DTC
The difference between the BARO sensor and the boost sensor is more than 20 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

Steps 1-3:

Steps 4-5:

Steps 6-9:

Steps 10-13:

Steps 14-18:

Steps 19-24:

The numbers below refer to the step numbers on the diagnostic table.
4. This step tests the ability of the BARO sensor to correctly indicate barometric pressure. The value shown for the BARO sensor varies with altitude.
6. This step tests for a sensor that is stuck in range.