{"product_id":"o2-oxygen-sensor-upstream-downstream-for-lincoln-navigator-1998-2008-5-4l","title":"O2 Oxygen Sensor Upstream Downstream for Lincoln Navigator (1998-2008) 5.4L","description":"\u003ch2 style=\"font-size: clamp(18px, 3vw, 21px); margin-bottom: 15px; line-height: 1.3;\"\u003eDirect-Fit O2 Oxygen Sensor Complete Set for 1998-2008 Lincoln Navigator (UN173\/U228\/U326)\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat it Does:\u003c\/strong\u003e The complete 4-piece O2 Oxygen Sensor Set replaces aged factory exhaust sensors on the 1998-2008 Lincoln Navigator to restore closed-loop fuel management, correct engine air-fuel ratios, and eliminate emissions-related check engine lights.\u003c\/p\u003e\n\n\u003ch3\u003eThe Stock Lincoln Navigator Sensor Degradation\u003c\/h3\u003e\n\u003cp\u003eFactory zirconia O2 sensors on the \u003cstrong\u003eLincoln Navigator\u003c\/strong\u003e degrade significantly after years of exposure to thermal cycling, unburnt hydrocarbons, and exhaust particulates. Over time, internal sensing elements experience silica and carbon fouling, leading to delayed switching response and skewed signal voltages. In the \u003cstrong\u003e5.4L Modular V8\u003c\/strong\u003e, sluggish upstream sensors cause the PCM to run overly rich or lean fuel trims, prompting rough idle, misfires, hesitation under load, reduced fuel economy, and diagnostic fault codes \u003cstrong\u003eP0130\u003c\/strong\u003e through \u003cstrong\u003eP0161\u003c\/strong\u003e. Concurrently, fouled downstream sensors trigger false catalytic converter failure codes such as \u003cstrong\u003eP0420\u003c\/strong\u003e and \u003cstrong\u003eP0430\u003c\/strong\u003e.\u003c\/p\u003e\n\n\u003ch3\u003eThe Engineering Solution\u003c\/h3\u003e\n\u003cp\u003eThis comprehensive set provides two upstream and two downstream oxygen sensors engineered specifically for high heat exposure and fast signal response. Each sensor features double-protected stainless steel housing to isolate internal ceramic thimbles from direct particulate fouling, ensuring precision voltage transmission across closed-loop operation. Pre-terminated wiring harnesses match factory pinouts and wire lengths, seating directly into original bungs without wire splicing or terminal repinning to ensure reliable signal fidelity and stable LTFT\/STFT parameters.\u003c\/p\u003e\n\n\u003ch3\u003eWhat's Included\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e2 Upstream Oxygen Sensors\u003c\/li\u003e\n  \u003cli\u003e2 Downstream Oxygen Sensors\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003cdiv style=\"overflow-x: auto; margin-bottom: 20px;\"\u003e\n  \u003ctable width=\"100 style=\" border-collapse: collapse border: solid font-size: min-width:\u003e\n    \u003ctr style=\"background-color: #f9f9f9;\"\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eFitment\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e1998-2008 Lincoln Navigator\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eEngine \/ Chassis\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e5.4L Modular V8 (2V\/3V) \/ UN173, U228, U326\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background-color: #f9f9f9;\"\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eStock Output\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e230-300 hp \/ 325-365 lb-ft\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eReplaces OEM Part #\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003eSG459, 234-4001, 234-4046, 234-4070, 234-4071, 234-4127, 234-4401, SG1801, SG1802, SG1803, SG1806, SG1807\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch3\u003eCompatibility\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e1998-2008 Lincoln Navigator 5.4L V8 Base \/ L (All Trims)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eFrequently Asked Questions \u0026amp; Fitment Warnings\u003c\/h3\u003e\n\u003ch4\u003eDoes this fit the UN173, U228, and U326 Navigator?\u003c\/h4\u003e\n\u003cp\u003eYes, this is a direct fit for the 1998-2008 Lincoln Navigator equipped with the \u003cstrong\u003e5.4L Modular V8\u003c\/strong\u003e engine across all chassis generations within these model years.\u003c\/p\u003e\n\n\u003ch4\u003eDo I need special tools or preparation to install these sensors?\u003c\/h4\u003e\n\u003cp\u003eUse a dedicated 7\/8-inch (22mm) slotted oxygen sensor socket, apply high-temperature anti-seize strictly to the threads while keeping the sensing tip uncontaminated, and route harness wiring safely away from exhaust heat shields.\u003c\/p\u003e\n\n\u003ch3\u003eThe Lincoln Durability Standard\u003c\/h3\u003e\n\u003cp\u003eEngineered for full-size luxury SUVs tasked with heavy hauling and towing demands, these sensors deliver exact real-time exhaust telemetry to maintain powertrain endurance and peak towing performance under sustained load.\u003c\/p\u003e","brand":"VelocityMax","offers":[{"title":"Default Title","offer_id":67910018531576,"sku":"DS-ENRB7IXN2","price":103.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0800\/1290\/2648\/files\/o2-oxygen-sensor-upstream-downstream-for-lincoln-navigator-1998-2008-5-4l-1.jpg?v=1793391796","url":"https:\/\/performancechiptuning.com\/products\/o2-oxygen-sensor-upstream-downstream-for-lincoln-navigator-1998-2008-5-4l","provider":"Performance Chip Tuning","version":"1.0","type":"link"}