2010 Cadillac CTS Sedan AWD V6-3.6L Page 1951
conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Engine operating, move the related HO2S harnesses for the appropriate HO2S 2 between the HO2S harness connector and the engine control
module (ECM) while monitoring the appropriate scan tool HO2S voltage parameter. Verify that the HO2S parameter does not change
abruptly while moving the related harnesses.
瀚慖f the HO2S parameter does change abruptly while moving the related harnesses repair the circuit as necessary.
2. Ignition OFF, disconnect the harness connector at the appropriate HO2S 2.
3. Ignition ON, verify that the scan tool HO2S 2 parameter is between 401-519 mV.
瀚慖f less than the specified range, test the signal circuit terminal B for a short to ground. If the circuit/connections test normal, replace the
ECM.
4. Verify that none of the following conditions exist:
* The vacuum hoses for splits, kinks, and proper connection
* The air intake system after the mass air flow (MAF) sensor for vacuum leaks
* Exhaust system leaks
* Lean fuel injectors-Refer to Fuel Injector Solenoid Coil Test (w/LLT) (See: Powertrain Management/Computers and Control
Systems/Testing and Inspection/Component Tests and General Diagnostics/Fuel Injector Solenoid Coil Test)Fuel Injector Solenoid Coil
Test (w/LF1) (See: Powertrain Management/Fuel Delivery and Air Induction/Fuel Injector/Testing and Inspection).
* Water intrusion in the HO2S harness connector
* Low fuel system pressure-Refer to Fuel System Diagnosis (See: Powertrain Management/Computers and Control Systems/Testing and
Inspection/Component Tests and General Diagnostics/Fuel System Diagnosis).
* Fuel that is contaminated-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) (See: Powertrain
Management/Computers and Control Systems/Testing and Inspection/Component Tests and General
Diagnostics/Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool))Alcohol/Contaminants-in-Fuel Diagnosis (without Special
Tool) (See: Powertrain Management/Computers and Control Systems/Testing and Inspection/Component Tests and General
Diagnostics/Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool)).
* Contaminated HO2S - Silicon
* An engine mechanical condition-Refer to Symptoms - Engine Mechanical (See: Engine, Cooling and Exhaust/Engine/Testing and
Inspection/Symptom Related Diagnostic Procedures/Symptoms - Engine Mechanical).
瀚慖f you find any of the above conditions, repair as necessary.
5. If all circuits/connections test normal, replace the appropriate HO2S.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (LF1) (See: Powertrain Management/Computers and Control Systems/Oxygen
Sensor/Service and Repair)Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (LLT) (See: Powertrain Management/Computers and
Control Systems/Oxygen Sensor/Service and Repair)
* Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (LF1) (See: Powertrain Management/Computers and Control Systems/Oxygen
Sensor/Service and Repair)Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (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
P2271
DTC P2271 or P2273 (w/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 P2271
- HO2S Signal Stuck Rich Bank 1 Sensor 2
