This O2 sensor adapter is designed for off-road use only and features a built-in mini catalytic converter. It helps prevent engine check lights that may appear after modifying or removing the exhaust's catalytic converter, including when installing a high-flow unit. The device works by simulating the signal of a functioning stock catalytic converter to the ECU, which can help avoid error codes such as P0420 or P0430 related to catalyst system efficiency. When the catalytic converter is removed, the rear oxygen sensor typically detects higher temperatures and increased unburned fuel flow, which can trigger the check engine light (SES) and diagnostic trouble codes (DTCs). This adapter with a mini catalyst helps manage these signals under certain conditions. Product Name: Car Oxygen O2 Sensor Adapter Product Size: As shown in images Product Color: As shown in images Product Material: Metal Thread Specification: M18 x 1.5 Packing List: 1 x Adapter Package Weight: 40g Note: All images are professionally shot. Due to variations in lighting and display settings, actual product color may vary slightly from photos. Measurements are taken manually and may have slight deviations, but this does not affect functionality.