2010 Cadillac CTS Sedan AWD V6-3.6L Page 802

2010 Cadillac CTS Sedan AWD V6-3.6L Page 802

* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an

overview of the diagnostic approach.

* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure

Instructions) provides an overview of each diagnostic category.

DTC Descriptors

DTC P0131

- HO2S Circuit Low Voltage Bank 1 Sensor 1

DTC P0132

- HO2S Circuit High Voltage Bank 1 Sensor 1

DTC P0137

- HO2S Circuit Low Voltage Bank 1 Sensor 2

DTC P0138

- HO2S Circuit High Voltage Bank 1 Sensor 2

DTC P0151

- HO2S Circuit Low Voltage Bank 2 Sensor 1

DTC P0152

- HO2S Circuit High Voltage Bank 2 Sensor 1

DTC P0157

- HO2S Circuit Low Voltage Bank 2 Sensor 2

DTC P0158

- HO2S Circuit High Voltage Bank 2 Sensor 2

DTC P2A00

- HO2S Circuit Closed Loop Performance Bank 1 Sensor 1

DTC P2A03

- HO2S Circuit Closed Loop Performance Bank 2 Sensor 1

Diagnostic Fault Information

Typical Scan Tool Data

Circuit/System 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. While the engine runs, the HO2S heats up and begins to generate a voltage within a

range of 0-1,275 mV. 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 toward 1,000 mV indicates a rich fuel mixture. An HO2S

voltage that decreases 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.