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 conditions similar to those of an original catalytic converter. When the catalytic converter is removed, the rear O2 sensor may detect changes in temperature and 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 legal for use on public roads. It may take time to become fully operational. Check engine light issues can also stem from O2 sensor problems, such as over-sensitive sensors, which may cause the light to remain on after installation and lead to additional error codes. Therefore, this CEL simulator is designed to address only certain catalytic converter efficiency-related codes, primarily P0420, which is the most common cause.1. Threads are precision-machined for accurate fitment. 2. Simple design made 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.