Do not use extensions as they may not function properly; this is a built-in mini catalytic converter. This O2 check engine light (CEL) fixture with a miniature catalytic converter helps the ECU detect that the catalytic converter is still in place. When the catalytic converter is removed, the rear O2 sensor can detect higher temperatures and increased unburned fuel flow, potentially triggering a check engine light (CEL), commonly with error codes P0420 (catalyst system efficiency below threshold, bank 1) and/or P0430 (catalyst system efficiency below threshold, bank 2). This device is intended for off-road use only and is not designed for use on public roads. It may take time to become fully operational. However, CEL alerts can sometimes be caused by O2 sensor issues, such as over-sensitive sensors. In such cases, the light may remain on even after installation, potentially leading to additional error codes. Therefore, this CEL simulator (also known as a mini cat) cannot resolve all check engine light issues. It is designed to address only the P0420 code related to catalytic converter efficiency, which is the most common cause. 1. Threads are precision-machined using specialized tools for accurate fitment. 2. Simple design with high-quality materials, resistant to deformation and rust. 3. Universal fit for most vehicles with 18mm x 1.5 O2 sensor bungs. 4. Constructed from high-strength, durable metal. 5. Easy installation with direct bolt-on design; no modifications required. Condition: New Type: O2 Sensor Gasket Adapter Thread: 18mm x 1.5 Material: Metal Color: Silver Package Contents: 2 x Oxygen Sensor Adapters Note: The package includes only the items listed above. Other accessories are not included. Note: Lighting effects and display settings may cause slight variations in color between the image and the actual item. Measurement may vary by +/- 1-3 cm.