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 system’s catalytic converter, including when installing a high-flow unit. The device works by simulating the signal of a functioning catalytic converter to the vehicle's ECU, which can help avoid error codes such as P0420 or P0430 related to catalyst system efficiency below threshold. When the catalytic converter is removed, the rear oxygen sensor typically detects changes in temperature and unburned fuel flow, which can trigger the check engine light (CEL), SES, or DTC codes. 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 manually taken and may have slight deviations, but this does not affect functionality.