{"product_id":"o2-oxygen-sensor-upstream-downstream-for-subaru-legacy-outback-2010-2012-2-5l","title":"O2 Oxygen Sensor Upstream Downstream for Subaru Legacy Outback (2010-2012) 2.5L","description":"\u003ch2 style=\"font-size: clamp(18px, 3vw, 21px); margin-bottom: 15px; line-height: 1.3;\"\u003eDirect-Fit Upstream \u0026amp; Downstream O2 Oxygen Sensor Kit for 2010-2012 Subaru Legacy \u0026amp; Outback (BM\/BR)\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eWhat it Does:\u003c\/strong\u003e This matched upstream and downstream oxygen sensor kit monitors pre- and post-catalyst exhaust gas oxygen on the 2010-2012 Subaru Legacy and Outback (\u003cstrong\u003eBM\/BR\u003c\/strong\u003e) equipped with the \u003cstrong\u003eEJ253 2.5L\u003c\/strong\u003e engine to regulate closed-loop fuel trims and verify catalytic converter efficiency.\u003c\/p\u003e\u003ch3\u003eThe Stock Subaru Legacy \u0026amp; Outback Oxygen Sensor Failure\u003c\/h3\u003e\u003cp\u003eOver high-mileage thermal cycles on the \u003cstrong\u003eBM\/BR\u003c\/strong\u003e chassis equipped with the naturally aspirated \u003cstrong\u003eEJ253 2.5L H4\u003c\/strong\u003e engine, factory oxygen sensors suffer from zirconia ceramic cracking, carbon fouling, and internal heater burnout. Oil mist or exhaust condensation coats the sensing element, slowing voltage response and skewing closed-loop fuel trim calculations. This degradation commonly triggers heater circuit and slow-response fault codes including \u003cstrong\u003eP0031\u003c\/strong\u003e, \u003cstrong\u003eP0037\u003c\/strong\u003e, \u003cstrong\u003eP0137\u003c\/strong\u003e, and \u003cstrong\u003eP0420\u003c\/strong\u003e.\u003c\/p\u003e\u003ch4\u003eCommon Symptoms of a Failing OEM Oxygen Sensor\u003c\/h4\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eCheck Engine Light \u0026amp; Heater Faults:\u003c\/strong\u003e Triggers \u003cstrong\u003eP0031\u003c\/strong\u003e, \u003cstrong\u003eP0037\u003c\/strong\u003e, or \u003cstrong\u003eP0137\u003c\/strong\u003e when internal heater coils open or post-cat voltage flatlines.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eErratic Closed-Loop Fueling:\u003c\/strong\u003e Sluggish upstream air-fuel feedback causes rich running conditions, fouled spark plugs, and reduced fuel economy.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFailed Emissions Inspection:\u003c\/strong\u003e Compromised sensor signals prevent OBD-II readiness monitors from setting and trigger \u003cstrong\u003eP0420\u003c\/strong\u003e catalyst efficiency warnings.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eThe Direct-Fit Heated Zirconia Oxygen Sensor Solution\u003c\/h3\u003e\u003cp\u003eEngineered as a matched replacement for OEM numbers \u003cstrong\u003e234-9097\u003c\/strong\u003e (upstream) and \u003cstrong\u003e234-4445\u003c\/strong\u003e (downstream), this direct-fit sensor kit restores factory ECU signal fidelity on the \u003cstrong\u003eEJ253\u003c\/strong\u003e platform. Each sensor utilizes a high-temperature stainless steel housing, laser-welded protective shroud, and fast-acting internal heater element to withstand exhaust heat soak. Pre-terminated factory 4-wire connectors and anti-seize coated threads ensure bolt-on installation without cutting or splicing.\u003c\/p\u003e\u003ch3\u003eWhat's Included\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e1 Upstream Oxygen Sensor (Replaces \u003cstrong\u003e234-9097\u003c\/strong\u003e)\u003c\/li\u003e\n\u003cli\u003e1 Downstream Oxygen Sensor (Replaces \u003cstrong\u003e234-4445\u003c\/strong\u003e)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\u003cdiv style=\"overflow-x: auto; margin-bottom: 20px;\"\u003e\u003ctable width=\"100%\" style=\"border-collapse: collapse; border: 1px solid #e0e0e0; font-size: 14px; min-width: 300px;\"\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;\"\u003e2010-2012 Subaru Legacy \u0026amp; Outback\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;\"\u003eEJ253 2.5L Naturally Aspirated H4 \/ BM, BR\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;\"\u003eSensor Architecture\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003eUpstream Air-Fuel Ratio (A\/F) \u0026amp; Downstream Heated Zirconia (4-Wire)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eInstallation Type\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003eDirect Bolt-On OEM Replacement (No Cutting or Welding)\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;\"\u003eReplaces OEM Part #\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e234-9097, 234-4445\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003c\/div\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e2010-2012 Subaru Legacy 2.5L Naturally Aspirated (\u003cstrong\u003eBM\u003c\/strong\u003e Chassis, \u003cstrong\u003eEJ253\u003c\/strong\u003e Engine)\u003c\/li\u003e\n\u003cli\u003e2010-2012 Subaru Outback 2.5L Naturally Aspirated (\u003cstrong\u003eBR\u003c\/strong\u003e Chassis, \u003cstrong\u003eEJ253\u003c\/strong\u003e Engine)\u003c\/li\u003e\n\u003cli\u003eExcludes 2.5L Turbocharged and 2010-2014 3.6L models\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions \u0026amp; Fitment Warnings\u003c\/h3\u003e\u003ch4\u003eDoes this fit the BM\/BR Legacy and Outback?\u003c\/h4\u003e\u003cp\u003e\u003cstrong\u003eYes.\u003c\/strong\u003e This is a direct fit for the 2010-2012 Subaru Legacy and Outback equipped with the naturally aspirated \u003cstrong\u003eEJ253 2.5L\u003c\/strong\u003e engine. \u003cstrong\u003eDoes not fit 2.5L Turbocharged (\u003cstrong\u003eEJ255\u003c\/strong\u003e) or 2010-2014 3.6L (\u003cstrong\u003eEZ36D\u003c\/strong\u003e) models; confirm engine before ordering.\u003c\/strong\u003e\u003c\/p\u003e\u003ch4\u003eWill this clear P0031, P0037, or P0420 codes?\u003c\/h4\u003e\u003cp\u003e\u003cstrong\u003eYes, when caused by sensor failure.\u003c\/strong\u003e Replacing \u003cstrong\u003e234-9097\u003c\/strong\u003e and \u003cstrong\u003e234-4445\u003c\/strong\u003e resolves open heater circuits (\u003cstrong\u003eP0031\u003c\/strong\u003e\/\u003cstrong\u003eP0037\u003c\/strong\u003e) and slow-response faults, though a damaged catalytic converter will still trigger \u003cstrong\u003eP0420\u003c\/strong\u003e.\u003c\/p\u003e\u003ch4\u003eAre OEM connectors included for installation?\u003c\/h4\u003e\u003cp\u003e\u003cstrong\u003eYes.\u003c\/strong\u003e Both sensors include factory 4-pin harness plugs and pre-applied thread anti-seize; torque to approximately 30 ft-lbs on a cool exhaust.\u003c\/p\u003e\u003ch3\u003eThe Subaru Precision Standard\u003c\/h3\u003e\u003cp\u003eBuilt for the \u003cstrong\u003eBM\/BR\u003c\/strong\u003e symmetrical boxer drivetrain, this matched sensor kit restores closed-loop fueling precision and emissions compliance. Eliminate chronic check engine lights and maintain reliable daily performance.\u003c\/p\u003e","brand":"VelocityMax","offers":[{"title":"Default Title","offer_id":68116122140920,"sku":"DS-ERZ1JH8BW","price":56.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0800\/1290\/2648\/files\/o2-oxygen-sensor-upstream-downstream-for-subaru-legacy-outback-2010-2012-2-5l-1.jpg?v=1794710764","url":"https:\/\/performancechiptuning.com\/products\/o2-oxygen-sensor-upstream-downstream-for-subaru-legacy-outback-2010-2012-2-5l","provider":"Performance Chip Tuning","version":"1.0","type":"link"}