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 P0132: HO2S Circuit High Voltage Bank 1 Sensor 1
DTC P0152: HO2S Circuit High Voltage Bank 2 Sensor 1

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
HO2S Bank 1 Sensor 1 Signal | P0131 | P0134, P0135 | P0132 | P0133, P2096, P2097
HO2S Bank 1 Sensor 2 Signal | P0137 | P0140 | P0138 | P0140
HO2S Bank 2 Sensor 1 Signal | P0151 | P0154, P0155 | P0152 | P0153, P2098, P2099
HO2S Bank 2 Sensor 2 Signal | P0157 | P0160 | P0158 | P0160
Low Reference | -- | P0134, P0135, P0154, P0155 | -- | --

### Typical Scan Tool Data

#### HO2S 1 or 2

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Engine operating in Closed Loop Parameter Normal Range: Fluctuates above and below 350-500 mV
Sensor Signal | 0-60 mV | 445-450 mV | 1275 mV
Low Reference | -- | 445-480 mV | 1275 mV

### Circuit Description

The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the control module operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air-to-fuel ratio. The control module supplies the HO2S with a reference, or bias voltage of about 450 mV. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1,000 mV. This voltage will fluctuate above and below the bias voltage. Once sufficient HO2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control module uses the HO2S voltage to determine the air-to-fuel ratio. An HO2S voltage that increases above bias voltage toward 1,000 mV indicates a rich fuel mixture. An HO2S voltage that decreases below bias voltage toward 0 mV indicates a lean fuel mixture.

The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed Loop earlier and the control module to calculate the air-to-fuel ratio sooner.

### Conditions for Running the DTC

• | DTC P0201, P0202, P0203, P0204, P0205, P0206 P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, P0277, P2146, P2149, P2152, P2155, P216A, or P216D is not set.

• | The engine speed is greater than 240 RPM.

• | The ignition voltage is greater than 10 volts.

• | The HO2S 1 heater duty cycle is greater than 90 percent for greater than 5 seconds.

• | The ECM is not commanding the air/fuel mixture rich.

• | DTC P0132 and P0152 run continuously once the conditions above exist for greater than 5 seconds.

### Conditions for Setting the DTC

The ECM detects that an HO2S 1 signal voltage is greater than 1,150 mV.

### Action Taken when the DTC Sets

DTCs P0132 and P0152 are Type B DTCs.

### Conditions for Clearing the MIL/DTC

DTCs P0132 and P0152 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. Engine idling, observe the appropriate scan tool HO2S 1 voltage parameter. The voltage should fluctuate above and below the range of 350-550 mV.
2. 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. Ignition OFF, disconnect the harness connector at the appropriate HO2S.
2. Ignition ON, verify that the scan tool HO2S 1 voltage parameter is between 350-500 mV.

⇒ | If less than the specified range, test the signal circuit for a short to ground. If the circuit/connections test normal, replace the ECM.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.

3. Install a 3 A fused jumper wire between the signal circuit terminal B and ground. Verify the scan tool HO2S 1 voltage parameter is less than 60 mV.

⇒ | If greater than the specified range, test the signal circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.

4. Connect a 3 A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool HO2S 1 voltage parameter is less than 60 mV.

⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance or for a short to voltage. If the circuit/connections test normal, replace the ECM.

5. Verify that the following conditions do not exist:

• | Leaking fuel injectors.

• | High fuel system pressure--Refer to Fuel System Diagnosis.

• | Fuel that is contaminated--Refer to Alcohol/Contaminants-in-Fuel Diagnosis.

• | Restricted exhaust.

⇒ | If you find any of the above conditions, repair as necessary.

6. If all circuits/connections test normal, replace the appropriate HO2S 1.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Heated Oxygen Sensor Replacement - Bank 1 Sensor 1

• | Heated Oxygen Sensor Replacement - Bank 2 Sensor 1

• | Control Module References for engine control module replacement, setup, and programming