Faulty Oxygen Sensor: The replacement oxygen sensor may be defective or not compatible with your vehicle. Ensure the sensor is the correct part for your Cavalier and is properly installed.
Wiring Issues: Check the wiring harness connected to the oxygen sensor. Look for loose connections, damaged wires, or corrosion. Repair or replace any faulty wiring as needed.
Other Sensor Issues: Other sensors in the vehicle's emission control system, such as the mass airflow sensor (MAF) or throttle position sensor (TPS), could be faulty and causing the check engine light to remain illuminated.
ECM Problems: The Engine Control Module (ECM) may need to be reset or updated after replacing the oxygen sensor. Some vehicles require a scan tool or specific procedures to clear the check engine light after certain repairs.
Catalytic Converter: A faulty catalytic converter can also trigger the check engine light. If the catalytic converter is clogged or damaged, it may not be able to properly clean the exhaust gases, leading to an illuminated check engine light.
Vacuum Leaks: Vacuum leaks in the engine or emission control system can cause the engine to run lean, leading to oxygen sensor issues and a check engine light. Check for any leaks and repair as necessary.
Fuel Injector Problems: Faulty fuel injectors can affect the air-fuel mixture and cause the oxygen sensor to read incorrect values, leading to a check engine light.
O2 Sensor Signal Circuit: The signal circuit from the oxygen sensor to the ECM could have issues. Check the circuit for any breaks, shorts, or poor connections.
Exhaust System Leaks: Leaks in the exhaust system can affect the oxygen sensor readings and cause the check engine light to stay on. Ensure the exhaust system is properly connected and free from leaks.
Diagnostic Trouble Codes (DTCs): Connect a scan tool to the vehicle to retrieve any diagnostic trouble codes (DTCs) stored in the ECM. These codes can provide more information about the specific cause of the check engine light.
If you are unable to determine the exact cause of the check engine light, it's best to consult a qualified mechanic or automotive technician for further diagnosis and repair.
