2010 Cadillac CTS Sedan AWD V6-3.6L Page 1096

2010 Cadillac CTS Sedan AWD V6-3.6L Page 1096

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

programming

P0153

DTC P0133 or P0153 (with LLT)

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 P0133

- HO2S Slow Response Bank 1 Sensor 1

DTC P0153

- HO2S Slow Response Bank 2 Sensor 1

Diagnostic Fault Information

Circuit 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. The control module supplies the HO2S with a reference, or bias voltage of about 450

mV. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1,000 mV. This voltage will fluctuate above

and below the bias voltage. 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 above bias voltage toward 1,000 mV indicates a

rich fuel mixture. An HO2S voltage that decreases below bias voltage 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.

Conditions for Running the DTCs

* Before the ECM can report that DTC P0133 or P0153 failed, DTCs P0030, P0031, P0032, P0050, P0051, P0052, P0135, and P0155 must run

and pass.

* DTC P0036, P0037, P0038, P0057, P0058, P0130, P0137, P0138, P0140, P0141, P0150, P0157, P0158, P0160, P0161, P0300, P0301,

P0302, P0303, P0304, P0305, P0306, P0442, P0443, P0455, P0458, P0459, P2096, P2097, P2098, P2099, P2177, P2178, P2179, P2088,

P2089, P2090, P2232, P2235, P2270, P2271, P2272, or P2273 is not set.

* The engine speed is 1,200-2,520 RPM.

* The closed loop fuel control is enabled.

* The engine load is 13-55 percent.

* The exhaust gas temperature is warmer than 350掳C (662掳F).

* The evaporative purge (EVAP) solenoid is commanded OFF, or is ON for greater than 10 seconds.

* DTC P0133 and P0153 run continuously once the conditions above exist.

Conditions for Setting the DTCs

The ECM determines that the length of time for a primary HO2S to switch from lean to rich and back to lean, which is called a switching cycle, has

exceeded a predetermined threshold. The condition exists for 2.5 cycles out of a 20 cycle test sample.

Action Taken when the DTCs Set

DTCs P0133 and P0153 are Type B DTCs.