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 wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust system and provides more information than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell, and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine control module (ECM) supplies a voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell in order to maintain a constant voltage in the oxygen sensing cell. The ECM monitors the voltage variation in the sensing cell and attempts to keep the voltage constant by increasing or decreasing the amount of current flow, or oxygen ion flow, to the pumping cell. By measuring the amount of current required to maintain the voltage in the sensing cell, the ECM can determine the concentration of oxygen in the exhaust. The HO2S voltage is displayed as a lambda value. A lambda value of 1 is equal to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1. When the fuel system is lean, the oxygen level will be high and the lambda signal will be high or more than 1. When the fuel system is rich, the oxygen level will be low, and the lambda signal will be low or less than 1. The ECM uses this information to maintain the correct air/fuel ratio. If there is an internal ECM condition with the integrated circuits for the HO2S, 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 more 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

• | Engine Control Module Connector End Views

• | Engine Controls 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

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Verification

1. Observe the DTC information with a scan tool. Verify that there are no other DTCs are set. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
2. Engine running for more than 1 minute, observe the DTC information with a scan tool. DTC P0053 or P0059 should not set.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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