This O2 sensor adapter is designed for off-road use only. It features a built-in mini catalytic converter that helps prevent engine check lights from appearing after exhaust modifications, including the removal or replacement of the original catalytic converter with a high-flow unit. The device works by simulating the signal of a functioning catalytic converter to the vehicle's ECU, which may help avoid error codes such as P0420 or P0430 related to catalyst system efficiency. The rear oxygen sensor detects changes in exhaust temperature and unburned fuel flow when the catalytic converter is removed. This adapter helps maintain a stable signal to keep the ECU from triggering diagnostic trouble codes (DTC) and the service engine soon (SES) light. Product name: Car Oxygen O2 Sensor Adapter Product size: As shown Product color: As shown Material: Metal Thread specification: M18 x 1.5 Packing list: 1 x Adapter Package weight: 40g Note: Images are professionally edited. Due to variations in lighting and display settings, there may be slight color differences between the actual item and the pictures. Measurements are taken manually and may vary slightly, but this does not affect functionality.