GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2009 🢒 Vibe - AWD 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P2195 or P2196

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 P2195: Heated Oxygen Sensor (HO2S) Signal Biased Lean Sensor 1

DTC P2196: Heated Oxygen Sensor (HO2S) Signal Biased Rich Sensor 1

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

HO2S 1 Input

P2195, P2237, P2238

P2237, P2238

P2196, P2237, P2239, P2253

P2237, P2238, P2A00

Low Reference

P0171, P2196, P2237, P2239, P2252

P2237, P2238

P2196, P2237, P2238, P2239, P2253

P2237, P2238


Component

Cause

DTCs

Heated Oxygen Sensor 1
    • Low Fuel Pressure
    • Faulty Fuel Injector
    • Vacuum Leak
    • Exhaust Leak Near Sensor

P0171, P2195, P2A00

    • High Fuel Pressure
    • Faulty Fuel Injector
    • Exhaust Restriction

P0172, P2196, P2A00

Typical Scan Tool Data

HO2S 1

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: Engine operating in Closed Loop

Parameter Normal Range: Fluctuates between 3.2-3.4 volts/1.0 Lambda

HO2S 1 Input

1.232 Lambda/4.99 volts*

0.999 Lambda/3.3-3.4 volts

0.999 Lambda/0.00 volts**

Low Reference

1.232 Lambda/4.99 volts*

0.999 Lambda/2.9-3.2 volts

0.999 Lambda/0.00 volts**

*Actual circuit voltage is not the same as scan tool displayed voltage

**Actual circuit voltage is not the same as scan tool displayed voltage. Once DTC sets displayed voltage may default to fixed 3.30 volts.

Circuit Description

The heated oxygen sensor (HO2S) 1 is a wide band or wide range design. As with all oxygen sensors, the wide band HO2S measures the amount of oxygen in the exhaust system, but provides more information than the typical switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell, and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The powertrain control module (PCM) supplies a voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the PCM controls the pump current through the oxygen pumping cell in order to maintain a constant voltage in the oxygen sensing cell. The PCM monitors the voltage variation in the sensing cell and attempts to keep the voltage constant by increasing or decreasing the amount of current flow, or oxygen ion flow, to the pumping cell. By measuring the amount of current required to maintain the voltage in the sensing cell, the PCM can determine the concentration of oxygen in the exhaust. The HO2S input signal is displayed as a voltage within the range of 1-5 volts, with a steady value of 3.2-3.3 volts equal to the air fuel ratio of 14.7:1. If the HO2S 1 input voltage is lower than the specified reference voltage, the PCM determines that the air/fuel ratio is richer than the theoretical air/fuel ratio and reduces the fuel. If the input voltage from the HO2S 1 is higher than the specified reference voltage, the PCM determines that the air/fuel ratio is leaner and increases the fuel. By repeating these operations, the PCM can adjust the air/fuel ratio in order to be closer to the theoretical air/fuel ratio. Control of the fuel delivery system as just described is known as Closed Loop operation.

The HO2S utilizes the following circuits:

    • A signal circuit
    • A low reference circuit
    • An ignition 1 voltage circuit
    • A heater control circuit

Air Fuel Mixture

Exhaust O2 Content

HO2S 1 Output

Fuel System Response

Lean Mixture

High Oxygen

More Than 3.4 V

Rich Command

Rich Mixture

Low Oxygen

Less Than 3.2 V

Lean Command

Conditions for Running the DTC
    • DTCs P0031, P0032, P0037, P0038, P0100, P0101, P0102, P0103, P0110, P0112, P0113, P0115, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0171, P0172, P0220, P0222, P0223, P0300-P0304, P0335, P0339, P0340, P0341, P0441, P0443, P0455, P0456, P0500, P2135 are not set.
    • The engine has been running for more than 30 seconds.
    • The engine is operating in Closed Loop.
    • The DTCs run continuously when the above conditions have been met.

Conditions for Setting the DTC

P2195

The HO2S 1 input voltage is more than 3.8 volts for more than 2 seconds.

P2196

The HO2S 1 input voltage is less than 2.8 volts for more than 2 seconds.

Action Taken when the DTC Sets

DTCs  P2195 and P2196 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs  P2195 and P2196 are Type B DTCs.

Diagnostic Aids
    • Test for a contaminated oxygen sensor. Silicone and other contaminants can cause the oxygen sensor to provide false exhaust oxygen content readings. If contamination is found, determine the cause and correct the condition before replacing the HO2S.
    • The scan tool output control feature, Fuel Injector Modification, can be used at idle to check the oxygen sensor performance. Commanding the Fuel Injector Modification Commanded State to 25 percent should cause the HO2S 1 voltage to decrease to less than 3 volts. Changing the Fuel Injector Modification Commanded State to -12 percent should cause the HO2S 1 voltage to increase to more than 3.35 volts. An oxygen sensor that fails to respond accordingly may be faulty or contaminated. When performing the Fuel Injector Modification with the scan tool, the Loop Status will remain Open Loop and the Short Term FT will be fixed at 0 percent.
    • Test the HO2S 1 for water intrusion into the wiring harness and the sensor housing. Water can create a short to voltage in the HO2S signal circuit causing a false lean indication.

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 for scan tool information

Circuit/System Verification
  1. Ignition ON, observe the DTC information with a scan tool. Verify DTCs P2237, P2238, P2239, P2252, P2253 are not set.
    2. ⇒If DTC P2237, P2238, P2239, P2252, P2253 is set, diagnose the DTC first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle.
  2. Engine running at normal operating temperature, observe the scan tool HO2S 1 voltage parameter. The reading should fluctuate between 3.2-3.4 volts.
  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. Ignition OFF, disconnect the harness connector at the HO2S 1.
  2. Ignition ON, test for 3.4-3.6 volts between the HO2S 1 input circuit terminal 3 and ground.
    3. ⇒If less than the specified range, test the HO2S 1 input circuit for an open/high resistance or a short to ground. If the circuit tests normal, replace the PCM.
    ⇒If more than the specified range, test the HO2S 1 input circuit for a short to voltage. If the circuit tests normal, replace the PCM.
  3. Test for the following conditions:
    4. • Fuel contamination--Refer to Alcohol/Contaminants-in-Fuel Diagnosis.
    • Splits, kinks, or improper connections at the vacuum hoses
    • The fuel system operating pressure is incorrect--Refer to Fuel System Diagnosis.
    • The fuel injectors are operating lean or rich--Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F).
    • Vacuum leaks at the intake manifold, manifold fittings, or throttle body
    • Faulty crankcase ventilation system--Refer to Crankcase Ventilation System Inspection/Diagnosis.
    • A collapsed or restricted air intake duct and a restricted or dirty air filter
    • The incorrect operation of the evaporative emission control system--Refer to Evaporative Emission Control System Diagnosis.
  4. If all conditions test normal, replace the HO2S 1.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Heated Oxygen Sensor 1 Replacement
    •  Control Module References for control module replacement, setup, and programming