2010 Cadillac CTS Sedan AWD V6-3.6L Page 1101

2010 Cadillac CTS Sedan AWD V6-3.6L Page 1101

* Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (LF1) (See: Powertrain Management/Computers and Control Systems/Oxygen

Sensor/Service and Repair)Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (LLT) (See: Powertrain Management/Computers and

Control Systems/Oxygen Sensor/Service and Repair)

* Control Module References (See: Testing and Inspection/Programming and Relearning) for engine control module replacement, setup, and

programming

P0155

DTC P0135, P0141, P0155, or P0161

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System

Check - Vehicle) prior to using this diagnostic procedure.

* 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 P0135

- HO2S Heater Performance Bank 1 Sensor 1

DTC P0141

- HO2S Heater Performance Bank 1 Sensor 2

DTC P0155

- HO2S Heater Performance Bank 2 Sensor 1

DTC P0161

- HO2S Heater Performance Bank 2 Sensor 2

Diagnostic Fault Information

Circuit Description

The heated oxygen sensor (HO2S) heater reduces the time required for the oxygen sensor to reach operating temperature and maintains the

operating temperature during extended idle periods. When the ignition is turned to the ON position, ignition voltage is supplied directly to the

sensor heater. The engine control module (ECM) controls the heater operation by first modulating the control circuit to ground when the sensors are

cold. This prevents the possibility of thermal shock to the sensor, from condensation build-up on the sensor, by controlling the sensor's rate of

heating. After a predetermined amount of time, the ECM commands the heaters ON continuously. Once the sensor reaches operating temperature,

the ECM may modulate the heater control circuit to ground to maintain a desired temperature. The ECM controls the heater by grounding the

control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled up to voltage. The ECM can

determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

Conditions for Running the DTC

P0135 or P0155

* Before the ECM can report DTC P0135 or P0155 failed, P0030, P0031, P0032, P0050, P0051, and P0052 must run and pass.

* DTC P0130, P0131, P0132, P0134, P0150, P0151, P0152, or P0154 is not set.

* The engine speed is greater than 240 RPM.

* The ignition voltage is 10-18 volts.

* The intake air temperature (IAT) is greater than -30掳C (-22掳F).

* After the previous ignition cycle the engine OFF time was greater than 2 minutes, 0 seconds for LLT.

* The calculated exhaust temperature is between 300-750掳C (572-1,382掳F).

* The calculated exhaust temperature is colder than 750掳C (1,382掳F), for LLT.