P2096
DTC P2096 POST CATALYST FUEL TRIM SYSTEM TOO LEAN (BANK 1)
GENERAL DESCRIPTION
In order to provide the best possible combination of driveablity, fuel economy, and emission control, the PCM uses a closed loop air/fuel metering system. The PCM monitors the HO2S signal voltage and adjusts the fuel delivery based on the HO2S signal voltage in closed loop fuel control. Changes in fuel delivery will be indicated by the short-term and the long-term fuel trim values. The ideal fuel trim value is around 0%. The PCM will add fuel when the HO2S signal is indicating a lean condition. Additional fuel is indicated by fuel trim values that are above 0%. The PCM will reduce fuel when the HO2S signal is indicating a rich condition. Reduction in fuel is indicated by fuel trim values that are below 0%. The DTC relevant to fuel trim will be set when the value reaches excessive levels because of a lean or rich condition.
DTC DESCRIPTION
The PCM monitors the trim of lambda control by the rear HO2S signal in addition to the HO2S monitoring. The trim value calculation is based on the difference of rear HO2S signal from desired value. The PCM sets DTC P2096 if either trim value or the difference of rear HO2S from desired value is reached to the maximum threshold off the same error code is set in the next driving cycle, the PCM illuminates the MIL.
DTC Detecting Condition:
Signal Waveform & Data:
The HO2S(B1/B2) shows linear signal voltage because it detects emission gas purified by catalytic convertor.
MONITOR SCANTOOL DATA
1. Connect scantool to Data Link Connector(DLC).
2. Warm up the engine to normal operating temperature.
3. Monitor the HO2S (B1/B2) parameter on the scantool.
4. Is the same DTC displayed again?
YES: Go to "W/Harness Inspection" procedure
NO: Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
TERMINAL & CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES: Repair as necessary and go to "Verification of vehicle Repair" procedure.
NO: Go to "System inspection" procedure.
SYSTEM INSPECTION
1. Check Exhaust System Inspection
1. Visually/physically inspect the following conditions:
Exhaust system between HO2S (B1/S1) and Three way catalyst for air leakage
Damage, and for loose or missing hardware:
2. Was a problem found in any of the above areas?
YES: Repair as necessary and go to "Verification of vehicle Repair" procedure
NO: Go to "Component Inspection" procedure
COMPONENT INSPECTION
1. Check HO2S (B1/S1)
1. Ignition "OFF"
2. Remove HO2S(B1/S1)
3. Visually/physically inspect following items:
- Inspect the HO2S(B1IS1) for any silicon contamination. This contamination will be indicated by a white powdery coating and this will result in a but false voltage signal
- If contamination is evident on the HO2S (B1/S1), replace contaminated sensor
4. Was a problem found in any of the above areas?
YES: Repair as necessary and go to "Verification of vehicle Repair" procedure
NO: Go to "Check PCM" as below
2. Check PCM
1. Ignition "OFF"
2. Connect Scantool and Engine "ON"
3. Select simulation function on scantool.
4. Simulate voltage at terminal 2 of HO2S (B1/S2) sensor signal connector.
5. Is HO2S (B1/S2) signal value changed according to simulation voltage?
YES: Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage Repair or replace as necessary and then go to "Verification 9f Vehicle Repair" procedure.
NO: Substitute with a known-good PCM and check for proper operation. If the problem is corrected, replace PCM and then go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code (DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs.
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Monitor that all rediness test have been verified as "Complete.
5. Are any DTCs present?
YES: Go to the applicable troubleshooting procedure.
NO: System is performing to specification at this time.