For 1990-2009 cars

### 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 provide an overview of each diagnostic category.

### DTC Descriptors

DTC P2297: HO2S Performance During Decel Fuel Cut-Off Bank 1 Sensor 1
DTC P2298: HO2S Performance During Decel Fuel Cut-Off Bank 2 Sensor 1

### 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 fuel system is lean, the oxygen level will be high and the lambda signal will be high or greater than 1. When the fuel system is rich, the oxygen level will be low, and the lambda signal will be low or less than 1. The ECM uses this information to maintain the correct air/fuel ratio.

### Conditions for Running the DTC

#### Condition 1

• | Before the ECM can report DTC P2297 or P2298 failed, DTCs P0121, P0122, P0123, P0221, P0222, P0223, P0336, and P0338 must run and pass.

• | DTCs P0030, P0031, P0032, P0050, P0051, P0052, P0053, P0059, P0130, P0131, P0132, P0135, P0150, P0151, P0152, P0155, P0443, P0458, P0459, P2096, P2097, P2098, P2099, P2231, P2234, P2297, and P2298 are not set.

• | The HO2S is at operating temperature.

• | The HO2S is less than 1.06 lambda.

• | The engine is operating.

• | The fuel injectors are enabled.

• | The DTCs run continuously once the above conditions are met.

#### Condition 2

• | A decel fuel cut-off has occurred 10 times with successful adjustments.

• | The DTCs run continuously once the above conditions are met.

### Conditions for Setting the DTC

#### Condition 1

The ECM detects that the internal HO2S signal voltage is greater than 3.7 volts for greater than 10 seconds.

#### Condition 2

If the ECM detects that the compensation factor of the HO2S is less than -25 percent or greater than 30 percent of the expected value, this DTC sets.

### Action Taken when the DTCs Set

DTCs P2297 and P2298 are Type B DTCs.

### Conditions for Clearing the MIL/DTCs

DTCs P2297 and P2298 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 for scan tool information

### Circuit/System Verification

1. Ignition ON, observe the scan tool DTC information. Verify that no other DTCs are not set.

⇒ | If any other DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

2. 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 are captured in the Freeze Frame/Failure Records Data List.

### Circuit/System Testing

1. Verify that none of the following conditions exist:

• | Lean fuel injectors--Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2

• | Water intrusion in the HO2S harness connector

• | HO2S wiring harness damage

• | Incorrect RTV sealant

• | Low fuel system pressure--Refer to Fuel System Diagnosis

• | Fuel that is contaminated--Refer to Alcohol/Contaminants-in-Fuel Diagnosis

• | Fuel saturation of the evaporative emission (EVAP) canister

• | Exhaust leaks near the HO2S

• | Engine vacuum leaks

• | Engine oil consumption

• | Engine coolant consumption

⇒ | If you find any of the above conditions, repair as necessary.

2. If all conditions test normal, replace the appropriate HO2S.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Heated Oxygen Sensor Replacement - Bank 1 Sensor 1

• | Heated Oxygen Sensor Replacement - Bank 2 Sensor 1

• | Control Module References for engine control module replacement, setup, and programming