P2098
DTC P2096 or P2098
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptors
DTC P2096
- Post Catalyst Fuel Trim System Low Limit Bank 1
DTC P2098
- Post Catalyst Fuel Trim System Low Limit Bank 2
Diagnostic Fault Information
Typical Scan Tool Data
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 control module operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air-to-fuel ratio. The control module 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 control module, Closed Loop is entered. The control module 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.
Fuel trim bias is used by the ECM to keep the post catalyst HO2S voltage within a range of 580-665 mV. This allows optimal catalyst efficiency under light load conditions, such as at idle or a steady cruise. The ECM constantly monitors how lean or rich the fuel trim bias is commanded, to determine if the fuel trim bias is greater than a calibrated amount.
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
* Before the ECM can report DTC P2096 or P2098 failed, DTCs P0030, P0031, P0032, P0050, P0051, P0052, P0131, P0132, P0133, P0135, P0137, P0138, P013A, P013C, P013E, P014A, P0140, P0141, P0151, P0152, P0153, P0155, P0157, P0158, P0160, P0161, P2177, P2178, P2179, 2180, P2187, P2188, P2189, P2190, P2231, P2232, P2234, P2235, P2270, P2271, P2272, and P2273 must run and pass.
* DTC P0100, P0101, P0102, P0103, P0420, P0430, P0442, P0443, P0455, P0458, or P0459 is not set.
* The engine speed is 1,080-3,480 RPM.
* The engine load is 17-20 percent and steady.
* The closed loop fuel control is active for greater than 1 seconds.
* The front and rear HO2S are in Closed Loop.
* The calculated exhaust gas temperature is greater than 250°C (482°F).
* DTCs P2096 and P2098 run continuously when the conditions above have been met for greater than 200 seconds.
Conditions for Setting the DTC
The post catalyst fuel trim correction factor is biased lean by greater than 8 percent of the HO2S signal value for greater than 4 seconds or for a cumulative of 30 seconds.
Action Taken when the DTC Sets
DTCs P2096 and P2098 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P2096 and P2098 are Type B DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool DTC information. Verify DTCs P0137, P0138, or P0140 are not also set.
• If any of the above DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions) .
Caution: Refer to Road Test Caution (Road Test Warning) .
Important: The rear heated oxygen sensor (HO2S) must be in closed loop for this diagnostic to run. A road load condition is necessary to obtain closed loop.
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 you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Verify that none of the following conditions exist:
* Lean fuel injectors-Refer to Fuel Injector Balance Test with Special Tool (Fuel Injector Balance Test With Special Tool) or Fuel Injector Balance Test with Tech 2 (Fuel Injector Balance Test With Tech 2) .
* Water intrusion in the HO2S harness connector
* Low fuel system pressure-Refer to Fuel System Diagnosis (Component Tests and General Diagnostics) .
* Fuel that is contaminated-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) (Alcohol/Contaminants-In-Fuel Diagnosis (With Special Tool)) .
* Exhaust leaks near the HO2S
* Contaminated HO2S - Silicon
* Engine vacuum leaks
• If you find any of the above conditions, repair as necessary.
2. Ignition OFF, disconnect the harness connector at the appropriate HO2S 2.
3. Ignition ON, verify the appropriate scan tool HO2S 2 voltage parameter is between 350-550 mV.
• If less than the specified range, test the signal circuit for a short to ground. If the circuit/connections test normal, replace the ECM.
4. Connect the harness connector at the HO2S 2.
5. Engine idling, raise the engine speed above 1,200 RPM for 30 seconds. Verify the appropriate scan tool HO2S 2 voltage parameter is greater than 60 mV.
• If less than the specified value, replace the HO2S 2.
6. Engine idling, move the appropriate HO2S 1 and HO2S 2 harnesses between the HO2S harness connectors and the ECM. Observe the suspected scan tool HO2S 1 voltage parameter, and the HO2S 2 voltage parameter.
• If a parameter changes abruptly, repair the harness/connections as necessary.
7. If all circuits/connections test normal, replace the applicable HO2S 1.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (Service and Repair)
* Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (Service and Repair)
* Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (Service and Repair)
* Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (Service and Repair)
* Control Module References (Programming and Relearning) for engine control module replacement, setup, and programming