DTC P2096 or P2097
DTC P2096 or P2097
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions)provides an overview of each diagnostic category.
DTC Descriptors
DTC P2096 00
- Post Catalyst Fuel Trim System Low Limit Bank 1
DTC P2097 00
- Post Catalyst Fuel Trim System High Limit Bank 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 engine control module (ECM) operates in an open loop mode, ignoring the HO2S signal voltage while calculating the air-to-fuel ratio. The ECM 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 ECM, closed loop is entered. The ECM 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.
The HO2S utilizes the following circuits:
* A signal circuit
* A low reference circuit
* An ignition voltage circuit
* A heater control circuit
Conditions for Running the DTC
* The engine is running.
* The ignition voltage is greater than 10 V.
* The barometric pressure is greater than 72 kPa (10.44 PSI).
* The intake air temperature (IAT) sensor parameter is less than -40°C (-40°F).
Conditions for Setting the DTC
Long term fuel trim adjustment has reached its limit while the sensor voltage is still trying to move the adjustment further in the same direction.
Action Taken When the DTC Sets
DTCs P2096 00 and P2097 00 are Type B DTCs.
Conditions for Clearing the DTC
DTCs P2096 00 and P2097 00 are Type B DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning)for scan tool information
Circuit/System Verification
1. Ignition ON, observe the DTC information with a scan tool. DTCs P0131 00, P0132 00, P0134 00, P0137 00, P0138 00, or P0140 00 should not be set
• If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle) for further diagnosis.
2. Allow the engine to reach operating temperature. Operate the vehicle within the parameters specified in conditions for running the DTC. These DTCs should not set.
3. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.
Circuit/System Testing
1. Verify none of the following conditions exist
* Inspect the B52A Heated Oxygen Sensor 1 and B52B Heated Oxygen Sensor 2 for being secure
* Damaged wiring between either B52A Heated Oxygen Sensor 1 and B52B Heated Oxygen Sensor 2 and the K20 Engine Control Module
* Water intrusion in the B52A Heated Oxygen Sensor 1 and B52B Heated Oxygen Sensor 2 harness connectors
* Lean or rich fuel injectors-Refer to Fuel Injector Diagnosis (Fuel Injector Diagnosis).
* Low or high fuel system pressure-Refer to Fuel System Diagnosis (Fuel System Diagnosis).
* Fuel that is contaminated-Refer Alcohol/Contaminants-in-Fuel Diagnosis (Alcohol/Contaminants-in-Fuel Diagnosis).
* Contaminated B52A Heated Oxygen Sensor 1 and B52B Heated Oxygen Sensor 2.
* Exhaust leaks near the B52A Heated Oxygen Sensor 1 and B52B Heated Oxygen Sensor 2
* Engine vacuum leaks
• If you find any of the above conditions, repair as necessary.
2. Ignition OFF, disconnect the harness connector at B52B Heated Oxygen Sensor 2.
3. Ignition ON, verify the scan tool HO2S 2 voltage parameter is between 350-550 mV.
• If less than the specified range, test the B52B Heated Oxygen Sensor 2 high signal circuit for a short to ground. If the circuit/connections test normal, replace the K20 Engine Control Module.
4. Connect the harness connector at B52B Heated Oxygen Sensor 2.
5. Engine idling, raise the engine speed above 1 200 RPM for 30 s. Verify the scan tool HO2S 2 voltage parameter is greater than 60 mV.
• If less than the specified range, replace the B52B Heated Oxygen Sensor 2.
6. Engine idling, move the B52A Heated Oxygen Sensor 1 and B52B Heated Oxygen Sensor 2 harnesses between the B52A Heated Oxygen Sensor 1 and B52B Heated Oxygen Sensor 2 harness connector and the K20 Engine Control Module. Observe the scan tool HO2S 1 and HO2S 2 voltage parameter. Verify neither parameter changes abruptly.
7. If all circuits/connections test normal, replace the B52A Heated Oxygen Sensor 1 or B52B Heated Oxygen Sensor 2.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Heated Oxygen Sensor Replacement - Sensor 1 (1.6L LDE, LXV, and 1.8L 2H0) (Heated Oxygen Sensor Replacement - Sensor 1)
* Heated Oxygen Sensor Replacement - Sensor 2 (Heated Oxygen Sensor Replacement - Sensor 2)
* Control Module References (Programming and Relearning)for ECM replacement, setup, and programming.