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 P0053: O2 Sensor Heater Resistance Range/Performance (Bank 1 Sensor 1)
DTC P0059: O2 Sensor Heater Resistance Range/Performance (Bank 2 Sensor 1)

### Circuit/System Description

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. A heating element inside the HO2S minimizes the time required for the sensor to reach operating temperature. Voltage is provided to the heater by an ignition voltage circuit through a fuse. With the engine running a ground is provided to the heater by the HO2S heater low control circuit, through a low side driver within the engine control module (ECM). The ECM commands the heater ON or OFF to maintain a specific HO2S operating temperature range.

The ECM determines the temperature by measuring the current flow through the heater and calculating the resistance. Based on the resistance the ECM can predict the sensor temperature. The sensors use pulse width modulation (PWM) to control the heater operation. The ECM calculates the heater resistance on a cold start. This diagnostic will only run once per ignition cycle. If the ECM detects that the heater calculated resistance is not within the expected range these DTC will be set.

### Conditions for Running the DTC

• | DTCs P0112, P0113, P0117, P0118 are not set.

• | The engine is running.

• | The ignition is OFF for greater than 10 hours.

• | The Engine Coolant Temperature (ECT) Sensor parameter is between -30°C and +45°C (-22°F and +113°F) at engine start-up.

• | The ECT Sensor parameter minus the Intake Air Temperature (IAT) Sensor parameter is less than 8°C (14°F) at engine start-up.

• | DTCs P0053 and P0059 run once per drive cycle when the above conditions are met.

### Conditions for Setting the DTC

The ECM detects that the affected HO2S heater low control circuit is not within a specified range at engine start-up.

### Action Taken when the DTC Sets

DTCs P0053 and P0059 are type A DTCs.

### Conditions for Clearing the MIL/DTC

DTCs P0053 and P0059 are type A 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

• | With the engine running at operating temperature, observe the HO2S Heater parameter with a scan tool and manipulate the related wiring and connectors.

⇒ | If manipulation does affect the parameter then repair the harness or connector.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate HO2S.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal a known ground.

⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, replace the HO2S.

3. Ignition OFF, verify that the test lamp is OFF between the heater low control circuit terminal of the appropriate HO2S and B+.

⇒ | If the test lamp illuminates, test the low control circuit for a short to ground.

4. Connect a test lamp between the heater low control circuit terminal of the appropriate HO2S and the B+ circuit terminal.
5. With the engine running, the test lamp should be ON steady or flashing.

⇒ | If the test lamp is not ON steady or flashing, test the low control circuit for a short to voltage and for open/high resistance. If the circuit tests normal, replace the ECM.

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

### 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 1 Sensor 2 .

• | Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 .

• | Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 .

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