The downstream oxygen (O2) sensor for a 2009-2010 Toyota Corolla 1.8L is primarily responsible for monitoring the efficiency of the catalytic converter. When scanning your car with an OBD-II diagnostics tool, this specific part is identified as Bank 1, Sensor 2.Part Specifications & Cross-ReferencesTo ensure you buy the exact matching component for your vehicle, look for these industry-standard interchange numbers [0.20]:Toyota OEM Part Number: 89465-12840 (also crosses with 89465-02330)Denso Part Number (Original Equipment Manufacturer): 234-4305Other Interchange Numbers: 250-24188, Configuration: 4-pin male connector, heated