For 1990-2009 cars

### Circuit Description

The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust system and provides more information than the 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 engine control module (ECM) 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 ECM controls the pump current through the oxygen pumping cell in order to maintain a constant voltage in the oxygen sensing cell. The ECM 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 ECM can determine the concentration of oxygen in the exhaust. The HO2S voltage is displayed as a lambda value. A lambda value of 1 is equal to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1. When the system is lean, the oxygen level will be high and the lambda value will be high or more than 1. When the system is rich, the oxygen level will be low, and the lambda value will be low, or less than 1. The ECM uses this information to maintain the correct air/ fuel ratio.

### DTC Descriptors

This diagnostic procedure supports the following DTCs:

• | DTC P2195 HO2S Signal Biased Lean Bank 1 Sensor 1

• | DTC P2197 HO2S Signal Biased Lean Bank 2 Sensor 1

### Conditions for Running the DTC

#### Conditions 1

• | Before the ECM can report DTC P2195 or P2197 failed, DTCs P0137, P0138, P0140, P0141, P0157, P0158, P0160, P0161, P2270, P2271, P2272, and P2273 must run and pass.

• | The front HO2S is more than 1.06 lambda.

• | The Short Term Fuel Trim is on the maximum limit.

• | The front and rear heated oxygen sensors are at operating temperature.

• | The accumulated engine exhaust mass is more than 200 grams.

• | DTC P2195 and P2197 run continuously once the above conditions are met for approximately 100 seconds.

#### Conditions 2

• | Before the ECM can report DTC P2195 or P2197 failed, DTCs P0137, P0138, P0140, P0141, P0157, P0158, P0160, P0161, P2270, P2271, P2272, and P2273 must run and pass.

• | The front HO2S is more than 1.06 lambda.

• | The rear HO2S short term fuel trim values is more than 0.003.

• | The rear heated oxygen sensors deterioration and circuit diagnostic is complete.

• | The rear HO2S fuel trim is active.

• | The front and rear heated oxygen sensors are at operating temperature.

• | The accumulated engine exhaust mass is more than 200 grams.

• | DTC P2195 and P2197 run continuously once the above conditions are met for approximately 100 seconds.

#### Conditions 3

• | Before the ECM can report DTC P2195 or P2197 failed, DTCs P0137, P0138, P0140, P0141, P0157, P0158, P0160, P0161, P2270, P2271, P2272, and P2273 must run and pass.

• | Desired Lambda is more than 1.04.

• | The front and rear heated oxygen sensors are at operating temperature.

• | Start the lambda closed loop control system.

• | The rear heated oxygen sensors circuit diagnostic is complete.

• | The rear HO2S short term fuel trim values is more than the minimum.

• | The front and rear heated oxygen sensors deterioration and circuit problem are not set.

• | The accumulated engine exhaust mass is more than 800 grams.

• | DTC P2195 and P2197 run continuously once the above conditions are met for approximately 2 seconds.

### Conditions for Setting the DTC

The ECM detects that the front HO2S is operating too lean while the rear is operating too rich and the voltage signal exceeds the specified value.

### Action Taken When the DTC Sets

• | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

• | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

### Conditions for Clearing the MIL/DTC

• | The control module turns OFF the malfunction indicator lamp (MIL) at the beginning of the fourth ignition cycle, after 3 ignition cycles that the diagnostic runs and does not fail.

• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• | A history DTC and related Freeze Frame data clears after 40 warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• | Clear the MIL and the DTC with a scan tool.

### Diagnostic Aids

• | Use the J 35616-A/BT-8637 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.

• | The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Engine Controls Component Views .

• | For an intermittent condition, refer to Intermittent Conditions .

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step determines if a condition exists.

2. This step is testing for a rear HO2S sensor circuit condition. A circuit condition sets this DTC.

3. This step is testing for an intermittent circuit condition. Thoroughly inspect the HO2S circuits for an intermittent circuit condition.

4. This step is testing for an intermittent circuit condition. Thoroughly inspect the HO2S circuits for an intermittent circuit condition.

#### DTC P2195 or P2197

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Allow the engine to reach operating temperature.
2. Operate the vehicle within the parameters specified in Conditions for Running the DTC.
3. Observe the diagnostic trouble code (DTC) information with a scan tool.

Did DTC P2195 or DTC P2197 fail this ignition?

--

Go to Step 4

Go to Step 3

3 |

1. Observe the Freeze Frame and/or the Failure records data for this DTC.
2. Turn the ignition OFF for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame and/or the Failure records data.

Does the DTC fail this ignition cycle?

--

Go to Step 4

Go to Diagnostic Aids

4 | Is DTC P0041, P0137, P0138, P0140, P0157, P0158, or P0160 also set? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | Go to Step 5
5 |

1. Operate the engine above 1,200 RPM for 30 seconds.
2. Observe the appropriate rear HO2S voltage with a scan tool.

Is the voltage more than the specified value?

60 mV

Go to Step 8

Go to Step 6

6 |

1. Turn OFF the ignition.
2. Disconnect the appropriate rear heated oxygen sensor (HO2S).
3. Turn the ignition switch ON, with the engine OFF.
4. Observe the appropriate rear HO2S voltage parameter with a scan tool.

Is the voltage within the specified range?

350-550 mV

Go to Step 12

Go to Step 7

7 | Test the appropriate rear HO2S signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 14
8 | Move the related HO2S harnesses for the front sensor between the HO2S harness connector and the engine control module (ECM) while monitoring the appropriate HO2S lambda parameter. Does the HO2S parameter change abruptly while moving the related harnesses? | -- | Go to Step 15 | Go to Step 9
9 | Move the related HO2S harnesses for the rear sensor between the HO2S harness connector and the ECM while monitoring the appropriate HO2S voltage parameter. Does the HO2S parameter change abruptly while moving the related harnesses? | -- | Go to Step 15 | Go to Step 10
10 |

1. Turn OFF the ignition.
2. Disconnect the front and rear heated oxygen sensors.
3. Inspect the front and rear heated oxygen sensors for the following conditions:

• | Damaged wiring between the HO2S and the ECM - An intermittent circuit condition may cause this DTC to set.

• | For terminal corrosion or water intrusion in the HO2S harness connectors

• | For the correct terminal tension

• | The HO2S is securely installed and not damaged.

• | For any exhaust leaks--Refer to Symptoms - Engine Exhaust .

4. Repair as necessary. Refer to Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 19

Go to Step 11

11 |

1. Disconnect the ECM.
2. Test the appropriate front heated oxygen sensor circuits for being shorted together between the HO2S connector and the ECM. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 19

Go to Step 13

12 | Test for shorted terminals and for poor connections at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 17
13 | Test for shorted terminals and for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 16
14 | Test for shorted terminals and for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 18
15 | Repair the circuit as necessary. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 19 | --
16 | Replace the HO2S. Refer to the appropriate procedure:

• | Heated Oxygen Sensor Replacement - Bank 1 Sensor 1

• | Heated Oxygen Sensor Replacement - Bank 2 Sensor 1

Did you complete the replacement?

--

Go to Step 19

--

17 | Replace the HO2S. Refer to the appropriate procedure:

• | Heated Oxygen Sensor Replacement - Bank 1 Sensor 2

• | Heated Oxygen Sensor Replacement - Bank 2 Sensor 2

Did you complete the replacement?

--

Go to Step 19

--

18 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 19 | --
19 |

1. Clear the DTCs with a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 20

20 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK