For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

DTC P2227: Barometric Pressure (BARO) Sensor Performance
DTC P2228: Barometric Pressure (BARO) Sensor Circuit Low Voltage
DTC P2229: Barometric Pressure (BARO) Sensor Circuit High Voltage

### Typical Scan Tool Data

Parameter Normal Range: At ignition ON, or with the engine running: 60-105 kPa, depending on altitude. Refer to Altitude Versus Barometric Pressure.

### Circuit Description

The barometric pressure (BARO) sensor is integrated within the engine control module (ECM). The BARO sensor voltage signal is converted by the ECM for display on the scan tool as the BARO Sensor kPa parameter. The BARO sensor signal varies, according to changes in altitude and atmospheric conditions. This gives the ECM an indication of the current barometric pressure. The ECM uses this information for numerous internal calculations. The ECM monitors the BARO sensor signal for voltages/pressures that are not within a normal range. The ECM also monitors the stability of the BARO sensor signal by comparing successive samples.

### Conditions for Running the DTC

#### P2227 - Engine Cranking

• | DTCs P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, P2176, P2228, or P2229 is not set.

• | The engine is cranking.

• | The engine OFF timer is greater than 4 seconds before cranking begins.

• | This DTC runs once per ignition cycle within the enabling conditions.

#### P2227 - Engine Running Rationality Test

• | DTCs P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, P2176, P2228, or P2229 is not set.

• | The engine speed is less than 1000 RPM.

• | The TP Sensor parameter is less than 24 percent.

• | The engine has been running for greater than 5 seconds.

• | This DTC runs continuously within the enabling conditions.

#### P2227 - Engine Running Range Test

• | DTCs P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, P2176, P2228, or P2229 is not set.

• | The engine has been running for greater than 5 seconds.

• | This DTC runs continuously within the enabling conditions.

#### P2228

• | The ignition is ON or the engine is running.

• | This DTC runs continuously within the enabling conditions.

#### P2229

• | The ignition is ON or the engine is running.

• | This DTC runs continuously within the enabling conditions.

### Conditions for Setting the DTC

#### P2227 - Engine Cranking

The ECM detects, when the engine is cranking, that the BARO sensor signal plus a calibrated threshold is not within range of a model derived from the BARO sensor, the MAP sensor, and the boost pressure sensor for more than 2 seconds.

#### P2227 - Engine Running Rationality Test

• | The ECM detects, when the engine is running, that the BARO sensor signal has increased or decreased by greater than 10 kPa from the previous ignition OFF, and the BARO sensor is not within a calibrated range of the boost pressure sensor for greater than 4 seconds continuously or 50 seconds cumulative.

| OR

• | The ECM detects, when the engine is running, that the BARO sensor signal has increased or decreased by greater than 5 kPa within 20 seconds, and the BARO sensor is not within a calibrated range of the boost pressure sensor for greater than 4 seconds continuously or 50 seconds cumulative.

#### P2227 - Engine Running Range Test

The ECM detects, when the engine is running, that the BARO sensor signal is less than or greater than a calibrated threshold for more than 4 seconds continuously or 50 seconds cumulative.

#### P2228

The ECM detects that the BARO sensor voltage signal is less than 0.2 volt for greater than 4 seconds continuously or 50 seconds cumulative.

#### P2229

The ECM detects that the BARO sensor voltage signal is greater than 4.87V for greater than 4 seconds continuously or 50 seconds cumulative.

### Action Taken When the DTC Sets

DTCs P2227, P2228, P2229 are Type B DTCs.

### Conditions for Clearing the MIL/DTC

DTCs P2227, P2228, P2229 are Type B DTCs.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition OFF for 90 seconds, determine the current vehicle testing altitude.
2. Ignition ON, engine OFF, observe the scan tool BARO parameter, Boost Pressure Sensor parameter, and MAP Sensor parameter. Compare the parameters to the Altitude Versus Barometric Pressure table. The parameters should be within the specified range indicated in the table.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

1. Inspect for any type of restriction, contamination, dirt, snow or ice buildup at the BARO sensor port that is located on the ECM housing.

⇒ | If a condition exists, carefully clean the area as needed.

2. Clear the DTC, and operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset.

⇒ | If the DTC will not clear or continues to reset, replace the K20 ECM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming