GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2007 🢒 Omega VE 🢒 DTC 🢒 DTC P2196 or P2198

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category

DTC Descriptors

DTC P2196: HO2S Signal Biased Rich Bank 1 Sensor 1

DTC P2198: HO2S Signal Biased Rich Bank 2 Sensor 1

Typical Scan Tool Data

HO2S 1 or 2

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: Engine operating in Closed Loop.

Parameter Normal Range: Fluctuates above and below 350-500 mV.

Sensor Signal

0-60 mV

400-415 mV

5000 mV

Low Reference

--

400-415 mV

5000 mV

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 engine control module (ECM) operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air/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/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 ECM to calculate the air/fuel ratio sooner.

Conditions for Running the DTCs

DTC P2196 or P2198

    • The ignition voltage is between 10-16  volts.
    • The engine is operating.

Conditions for Setting the DTCs

P2196 and P2198

The ECM detects that the H02S Signal voltage is high.

Action Taken when the DTC Sets

DTCs P2196 and P2198 are type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P2196 and P2198 are type B DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References

Circuit/System Verification
    • Allow the engine to reach operating temperature. Engine running, observe the affected HO2S parameter with a scan tool.
       - The HO2S 1 value should vary from below 200 mV to above 800 mV and respond to fuelling changes.
       - The HO2S 2 value should change more than 200 mV when the throttle is quickly cycled 3 times from Closed to wide open and back to Closed after running the engine at 1,500 RPM for 30 seconds.
    • If any HO2S heater DTCs are set, diagnose those DTCs first.
    • The affected HO2S may be damaged due to contamination. Prior to replacing the affected HO2S, inspect for the following sources of contamination:

Notice: Refer to Silicon Contamination of Heated Oxygen Sensors Notice in the Preface section.

       - A silicon contaminated HO2S
       - Engine oil consumption - Refer to Oil Consumption Diagnosis.
       - Engine coolant consumption - Refer to Loss of Coolant.

Circuit/System Testing
  1. Disconnect the affected HO2S.
  2. Ignition ON, measure for approximately 2-40 mV from the affected HO2S low signal circuit terminal to a known ground.
    3. ⇒If more than approximately 40 mV, test the affected HO2S low signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
    ⇒If less than approximately 2 mV, test the affected HO2S low signal circuit for high resistance. If the circuit tests normal, replace the ECM.
  3. Measure for approximately 450 mV from the affected HO2S high signal circuit terminal and a known ground.
    4. ⇒If more than approximately 450 mV, test the affected HO2S high signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
    ⇒If less than approximately 450 mV, test the affected HO2S high signal circuit for high resistance. If the circuit tests normal, replace the ECM.
  4. Install a 3A fusible link wire between the affected HO2S high signal circuit terminal and the affected HO2S low signal circuit terminal. The affected HO2S parameter should indicate 0 mV.
    5. ⇒If not 0 mV and all circuits and connectors test normal, replace the ECM.
  5. Install a test lamp between the affected HO2S high signal circuit terminal and battery voltage. The affected HO2S parameter should indicate approximately 1,095 mV.
    6. ⇒If not 1,095 mV and all circuits and connectors test normal, replace the ECM.
  6. If the ECM and all circuits test normal, replace the affected HO2S.

Repair Instructions

Perform the Diagnostic Repair Verification.

    •  Heated Oxygen Sensor Replacement - Bank 1 Sensor 1
    •  Heated Oxygen Sensor Replacement - Bank 2 Sensor 1
    •  Engine Control Module Replacement for engine control module replacement, setup and programming.