{"product_id":"o2-oxygen-sensor-upstream-downstream-for-mercury-mountaineer-1997-2010-4-0l-4-6l-5-0l","title":"O2 Oxygen Sensor Upstream Downstream for Mercury Mountaineer (1997-2010) 4.0L, 4.6L, 5.0L","description":"\u003ch2 style=\"font-size: clamp(18px, 3vw, 21px); margin-bottom: 15px; line-height: 1.3;\"\u003eDirect-Fit Replacement Oxygen Sensor Set for 1997-2010 Mercury Mountaineer (UN105 \/ U152 \/ U251)\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat it Does:\u003c\/strong\u003e The 4-piece direct-fit oxygen sensor set replaces degraded factory lambda sensors on the 1997-2010 Mercury Mountaineer to restore closed-loop fuel trim accuracy and clear emission-related check engine lights.\u003c\/p\u003e\n\n\u003ch3\u003eThe Stock Mercury Mountaineer Sensor Degradation\u003c\/h3\u003e\n\u003cp\u003eOver extended operating cycles, OEM oxygen sensors on the \u003cstrong\u003eUN105\u003c\/strong\u003e, \u003cstrong\u003eU152\u003c\/strong\u003e, and \u003cstrong\u003eU251\u003c\/strong\u003e chassis suffer from thermal fatigue, carbon poisoning, and silicone fouling. The factory zirconia ceramic sensing elements lose latency, leading to sluggish switching frequency between rich and lean conditions. This latency skews short-term (STFT) and long-term fuel trims (LTFT), causing excessive unburnt hydrocarbon wash down the cylinders, ruined catalytic converters, reduced fuel economy, and trouble codes ranging from \u003cstrong\u003eP0130\u003c\/strong\u003e through \u003cstrong\u003eP0161\u003c\/strong\u003e or false-positive \u003cstrong\u003eP0420\u003c\/strong\u003e\/\u003cstrong\u003eP0430\u003c\/strong\u003e codes.\u003c\/p\u003e\n\n\u003ch3\u003eThe Engineering Solution\u003c\/h3\u003e\n\u003cp\u003eThis comprehensive set provides replacement sensors featuring dual-layer porous ceramic filter diffusion barriers and laser-welded stainless steel bodies. Sized for factory bungs with exact wire leads and keyed connectors, these units require no cutting or splicing. Fast-acting integrated internal heaters achieve operational light-off temperature within seconds of cold starts, minimizing cold-start emissions. Fully cross-compatible with OEM standards such as \u003cstrong\u003e234-4001\u003c\/strong\u003e and \u003cstrong\u003eSG1813\u003c\/strong\u003e, this set stabilizes idle response, protects emissions equipment under heavy engine loads, and preserves stock AFR calibration.\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;\"\u003e1997-2010 Mercury Mountaineer\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;\"\u003e4.0L Cologne \/ 4.6L Modular \/ 5.0L Windsor (UN105 \/ U152 \/ U251)\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;\"\u003e160-292 hp \/ 225-315 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;\"\u003eSG1813, 234-4001, 234-4046, 234-4070, 234-4071, 234-4127, 234-4401, 22013, 22016, 22060, 22071, 22500\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\u003e1997-2010 Mercury Mountaineer 4.0L Cologne V6 (OHV \/ SOHC)\u003c\/li\u003e\n  \u003cli\u003e1997-2001 Mercury Mountaineer 5.0L Windsor V8\u003c\/li\u003e\n  \u003cli\u003e2002-2010 Mercury Mountaineer 4.6L Modular V8 (2V \/ 3V)\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 UN105, U152, and U251 Mountaineer?\u003c\/h4\u003e\n\u003cp\u003eYes, this set directly fits 1997-2010 Mercury Mountaineer models equipped with the \u003cstrong\u003e4.0L Cologne\u003c\/strong\u003e, \u003cstrong\u003e4.6L Modular\u003c\/strong\u003e, or \u003cstrong\u003e5.0L Windsor\u003c\/strong\u003e powertrains; verify connector keyways and bank layout prior to seating.\u003c\/p\u003e\n\n\u003ch4\u003eShould anti-seize compound be applied to the threads during installation?\u003c\/h4\u003e\n\u003cp\u003eApply anti-seize exclusively to the threaded collar while ensuring the ventilated sensor shield and tip remain completely free of grease or contamination.\u003c\/p\u003e\n\n\u003ch3\u003eThe Mercury Durability Standard\u003c\/h3\u003e\n\u003cp\u003eBuilt to handle severe duty cycles, continuous towing demands, and off-road chassis vibration, these oxygen sensors maintain accurate feedback loops to protect your SUV's drivetrain over the long haul.\u003c\/p\u003e","brand":"VelocityMax","offers":[{"title":"Default Title","offer_id":67910491013368,"sku":"DS-EH2SBZVDT","price":99.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0800\/1290\/2648\/files\/o2-oxygen-sensor-upstream-downstream-for-mercury-mountaineer-1997-2010-4-0l-4-6l-5-0l-1.jpg?v=1793392825","url":"https:\/\/performancechiptuning.com\/de\/products\/o2-oxygen-sensor-upstream-downstream-for-mercury-mountaineer-1997-2010-4-0l-4-6l-5-0l","provider":"Performance Chip Tuning","version":"1.0","type":"link"}