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 provide an overview of each diagnostic category.

### DTC Descriptors

DTC P0053: HO2S Internal Heater Resistance Bank 1 Sensor 1
DTC P0059: HO2S Internal Heater Resistance Bank 2 Sensor 1

### Circuit Description

The engine control module (ECM) supplies a voltage near 450 mV between the heated oxygen sensor (HO2S) high signal circuit and the low reference circuit. The HO2S varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.

The ECM monitors and stores the HO2S voltage information. The ECM evaluates the HO2S voltage samples in order to determine the amount of time that the HO2S voltage was out of range. The ECM compares the stored HO2S voltage samples taken within each sample period and determines if the majority of the samples are out of the operating range. If there is an internal ECM condition with the integrated circuits for the heated oxygen sensor, this DTC sets.

### Conditions for Running the DTC

• | Before the ECM can report DTC P0053 or P0059 failed, DTCs P0030, P0031, P0032, P0101, P0121, P0122, P0123, P0131, P0132, P0133, P0221, P0222, and P0223 must run and pass.

• | The engine is operating.

• | The ignition 1 voltage is between 10.5-18 volts.

• | The DTCs run continuously once the above conditions are met for 40 seconds.

### Conditions for Setting the DTC

• | There is an internal ECM condition with the integrated circuits for the HO2S sensor.

• | The condition exists for greater than 4 seconds.

### Action Taken When the DTC Sets

DTCs P0053 and P0059 are Type B DTCs.

### Conditions for Clearing the MIL/DTC

DTCs P0053 and P0059 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. Observe the scan tool DTC information. Verify that there are no other HO2S DTCs set. If there are any other DTCs set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
2. Engine running for greater than 1 minute, observe the scan tool DTC information. DTC P0053 or P0059 should not set.

⇒ | If DTCs P0053 or P0059 failed this ignition, replace the ECM.

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.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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