2010 Cadillac Truck SRX FWD V6-3.0L Page 2028

2010 Cadillac Truck SRX FWD V6-3.0L Page 2028

P2270

DTC P2270 or P2272 (LF1)

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 P2270

- HO2S Signal Stuck Lean Bank 1 Sensor 2

DTC P2272

- HO2S Signal Stuck Lean Bank 2 Sensor 2

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.