Buick Regal: DTC P2096 or P2097

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 Descriptor

DTC P2096

Post Catalyst Fuel Trim System Low Limit

DTC P2097

Post Catalyst Fuel Trim System High Limit

Circuit Description

Fuel trim bias is used to keep the post catalyst air/fuel ratio within a predetermined range. This allows optimal catalyst efficiency under various operating conditions. The engine control module (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.

Conditions for Running the DTC

• DTC P0016, P0017, P0030, P0036, P0053, P0054, P0101, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0119, P0128, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P013A, P013B, P013E, P013F, P0140, P0141, P015A, P015B, P0178, P0179, P0201, P0202, P0203, P0204, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0301, P0302, P0303, P0304, P0340, P0341, P0365, P0366, P0411, P0442, P0443, P0446, P0449, P0452, P0453, P0455, P0458, P0459, P0496, P0498, P0499, P111E, P1133, P1248, P1249, P124A, P124B, P2147, P2148, P2150, P2151, P2153, P2154, P2156, P2157, P219A, P2227, P2228, P2229, P2230, P2269, P2270, P2271, P2440, P2444, or P2A00 is not set.
• The barometric pressure (BARO) is greater than 70 kPa (10.2 PSI).
• The manifold absolute pressure (MAP) is between 0 - 200 kPa (0 - 29 PSI).
• The intake air temperature (IAT) is between - 20ºC and +200ºC (-4 and +392ºF).
• The start up engine coolant temperature is warmer than - 20ºC (- 4ºF).
• The fuel control intrusive diagnostics are not active.
• The engine is operating under light acceleration, heavy acceleration, or cruise conditions.
• DTCs P2096 and P2097 run continuously when the conditions above have been met.

Conditions for Setting the DTC

The correction limit for a condition causing a lean or rich air/fuel ratio has been exceeded.

Action Taken when the DTC Sets

DTCs P2096 and P2097 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P2096 and P2097 are Type B DTCs.

Diagnostic Aids

• The post catalyst fuel trim diagnostic is very sensitive to heated oxygen sensor (HO2S) design. A non-OE sensor or an incorrect part number may cause a DTC to set.
• Certain aftermarket air filters may cause a DTC to set.
• Certain aftermarket air induction systems or modifications to the air induction system may cause a DTC to set.
• Certain aftermarket exhaust system components may cause a DTC to set.

Reference Information

Schematic Reference

Engine Controls Wiring Schematics (LTG)

Connector End View Reference

Component Connector End View Index

Component View Reference

Powertrain Component 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.

2. Verify DTC P0420 is not set.

• If the DTC is set

Refer to: DTC P0420

• Go to next step: If the DTC is not set

3. Verify no other HO2S or fuel trim DTC is set.

• If any other HO2S or fuel trim DTC is set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

• Go to next step: If no other HO2S or fuel trim DTC is set

4. Verify DTC P2096 or P2097 is not set.

• If a DTC is set

Refer to Circuit/System Testing.

• Go to next step: If no DTC is set

5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed in the Freeze Frame/Failure Records data.

6. Verify DTC P2096 or P2097 is not set.

• If a DTC is set

Refer to Circuit/System Testing.

• Go to next step: If no DTC is set

7. All OK.

Circuit/System Testing

Inspect for the conditions listed below:

P2096

• Air intake duct collapsed or restricted.
• Air filter dirty or restricted.
• Objects blocking the throttle body.
• Excessive fuel in the crankcase. Change engine oil as necessary.
• Rich fuel injectors. Refer to Fuel Injector Diagnosis.
• Excessive fuel system pressure. Refer to Fuel System Diagnosis.
• Fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis.
• Fuel saturation of the evaporative emissions (EVAP) canister
• Stuck open or leaking EVAP purge valve
• Restricted exhaust. Refer to Symptoms - Engine Exhaust.
• Improperly operating crankcase ventilation system. Refer to Crankcase Ventilation System Inspection/Diagnosis.

P2097

• Exhaust system leaks. Refer to Symptoms - Engine Exhaust.
• Split, kinked, or improperly connected vacuum hoses
• Insufficient fuel in the tank
• Leaks in the air induction system and air intake ducts
• Missing air filter element
• Cracked evaporative canister
• Evaporative pipes plugged, obstructed, or leaking
• Crankcase ventilation system leaking. Refer to Crankcase Ventilation System Inspection/Diagnosis.
• Engine vacuum leaks
• Low fuel system pressure. Refer to Fuel System Diagnosis.
• Contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis.
• Lean fuel injectors. Refer to Fuel Injector Diagnosis.
• If a condition is found

Repair as necessary.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Perform the scan tool Fuel Trim Reset after completing the repair.

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