{"product_id":"ntk-25661-oxygen-sensor-downstream","title":"NTK 25661 Oxygen Sensor - Downstream","description":"\u003ch2\u003eDirect Fit Oxygen Sensor for Audi A8 Quattro\u003c\/h2\u003e\u003cp\u003eNTK Direct Fit Oxygen Sensor 25661 is a specific-fit, heated oxygen sensor built for downstream applications on the Audi A8 Quattro. It uses a threaded mounting design and a 4-wire configuration to match the original-style installation and signal requirements.\u003c\/p\u003e\u003ch2\u003eKey Features\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eDirect fit design for specific application coverage\u003c\/li\u003e\n\u003cli\u003eHeated oxygen sensor for faster operating response\u003c\/li\u003e\n\u003cli\u003e4-wire construction for OE-style signal control\u003c\/li\u003e\n\u003cli\u003eThreaded mounting type with 18 mm thread diameter\u003c\/li\u003e\n\u003cli\u003e74.75 in. wiring harness length\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eDetailed Description\u003c\/h2\u003e\u003cp\u003eNTK 25661 is part of the Direct Fit Oxygen Sensor line, which focuses on application-specific replacement parts with OE-style fit, form, and function. NTK is established under the NGK family of products and is recognized as a major original equipment oxygen sensor supplier. This sensor is manufactured and tested to meet or exceed OE specifications, making it a direct replacement choice for downstream service on the Audi A8 Quattro. This part cross-references Bosch 16982 and DENSO Auto Parts 234-4809 for the same application.\u003c\/p\u003e\u003cp\u003eFits 2005-2009 Audi A8 Quattro, downstream. Fits 2005-2009 Audi A8 Quattro, downstream.\u003c\/p\u003e\u003ch2\u003eWhat It Is Used For\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eReplacing a worn or slow-responding downstream oxygen sensor\u003c\/li\u003e\n\u003cli\u003eRestoring proper exhaust gas feedback to the engine control system\u003c\/li\u003e\n\u003cli\u003eAddressing sensor-related fault codes tied to mixture monitoring\u003c\/li\u003e\n\u003cli\u003eCorrecting drivability issues caused by inaccurate oxygen readings\u003c\/li\u003e\n\u003cli\u003eServicing OE-equivalent emissions control hardware\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eInstallation Notes and Tips\u003c\/h2\u003e\u003cp\u003eVerify the connector, wire count, and threaded mounting style before installation. Confirm the downstream location and cylinder-bank application shown in the fitment notes for the Audi A8 Quattro. Use the part number 25661 to match the correct sensor configuration before removal of the original unit.\u003c\/p\u003e\u003ch2\u003eQuality Assurance\u003c\/h2\u003e\u003cp\u003eNTK states that these oxygen sensors are extensively tested during manufacturing to help ensure quality and reliability that meet or exceed OE specifications.\u003c\/p\u003e","brand":"NTK","offers":[{"title":"Default Title","offer_id":53731440918709,"sku":"BFPZ-25661","price":113.93,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0628\/1442\/1173\/files\/NO_25661_Fro.jpg?v=1794296626","url":"https:\/\/www.partcatalog.com\/products\/ntk-25661-oxygen-sensor-downstream","provider":"PartCatalog","version":"1.0","type":"link"}