{"product_id":"o2-oxygen-sensor-upstream-downstream-for-kia-optima-2011-2015-2-4l","title":"O2 Oxygen Sensor Upstream Downstream for Kia Optima (2011-2015) 2.4L","description":"\u003ch2 style=\"font-size: clamp(18px, 3vw, 21px); margin-bottom: 15px; line-height: 1.3;\"\u003eDirect-Fit Upstream \u0026amp; Downstream O2 Sensor Kit for 2011-2015 Kia Optima (TF)\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eWhat it Does:\u003c\/strong\u003e Monitors exhaust air-fuel ratios on the \u003cstrong\u003e2011-2015 Kia Optima (TF)\u003c\/strong\u003e \u003cstrong\u003e2.4L GDI (G4KJ)\u003c\/strong\u003e to maintain closed-loop fuel trim and emissions compliance.\u003c\/p\u003e\u003ch3\u003eThe Stock Kia Optima Sensor Failure\u003c\/h3\u003e\u003cp\u003eOn the \u003cstrong\u003eTF\u003c\/strong\u003e chassis with the \u003cstrong\u003eTheta II 2.4L GDI (G4KJ)\u003c\/strong\u003e, the factory upstream (\u003cstrong\u003e234-5029\u003c\/strong\u003e) and downstream (\u003cstrong\u003e234-4238\u003c\/strong\u003e) sensors endure constant exhaust heat soak and carbon soot exposure. Over time, silicate contamination or internal heater element burnout degrades the zirconia ceramic element, slowing voltage switching response. Sluggish feedback skews ECU fuel trims and triggers fault codes like \u003cstrong\u003eP0135\u003c\/strong\u003e, \u003cstrong\u003eP0141\u003c\/strong\u003e, or false \u003cstrong\u003eP0420\u003c\/strong\u003e alerts.\u003c\/p\u003e\u003ch4\u003eCommon Symptoms of a Failing OEM O2 Sensor\u003c\/h4\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eCheck Engine Light \/ DTCs:\u003c\/strong\u003e Stored codes like \u003cstrong\u003eP0133\u003c\/strong\u003e, \u003cstrong\u003eP0135\u003c\/strong\u003e, \u003cstrong\u003eP0141\u003c\/strong\u003e, or \u003cstrong\u003eP0420\u003c\/strong\u003e from slow response or heater burnout.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eErratic Fueling:\u003c\/strong\u003e Delayed closed-loop transition causes rough idle and throttle hesitation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHigh Fuel Consumption:\u003c\/strong\u003e Over-rich mixtures lower MPG and risk catalytic converter thermal overload.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eThe Direct-Fit Matched O2 Sensor Solution\u003c\/h3\u003e\u003cp\u003eReplacing both sensors as a matched set restores factory closed-loop lambda control across the \u003cstrong\u003eTheta II 2.4L GDI (G4KJ)\u003c\/strong\u003e exhaust stream. Each unit uses a corrosion-resistant stainless steel housing, laser-welded shield, and rapid-heating zirconia element calibrated to match \u003cstrong\u003e39210-2C210\u003c\/strong\u003e, \u003cstrong\u003e39210-2G100\u003c\/strong\u003e, and \u003cstrong\u003e39210-2G200\u003c\/strong\u003e resistance specs. Direct-fit harnesses and OEM connectors eliminate splicing for clean signal transmission to the \u003cstrong\u003eTF\u003c\/strong\u003e ECU.\u003c\/p\u003e\u003ch3\u003eWhat's Included\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e1 Upstream Oxygen Sensor (\u003cstrong\u003e234-5029\u003c\/strong\u003e)\u003c\/li\u003e\n\u003cli\u003e1 Downstream Oxygen Sensor (\u003cstrong\u003e234-4238\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;\"\u003e2011-2015 Kia Optima\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;\"\u003e2.4L GDI (G4KJ) \/ TF\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;\"\u003eEmissions \u0026amp; Sensor Spec\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003eHeated Zirconia \/ Direct-Fit Matched Set\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\/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;\"\u003e234-4238, 234-5029, 39210-2C210, 39210-2G100, 39210-2G200\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003c\/div\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e2011-2015 Kia Optima (\u003cstrong\u003eTF\u003c\/strong\u003e) — \u003cstrong\u003e2.4L\u003c\/strong\u003e Naturally Aspirated (\u003cstrong\u003eG4KJ\u003c\/strong\u003e)\u003c\/li\u003e\n\u003cli\u003eExcludes 2016 models, 2.0L Turbo, and other Hyundai\/Kia vehicles.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions \u0026amp; Fitment Warnings\u003c\/h3\u003e\u003ch4\u003eDoes this fit the TF Optima?\u003c\/h4\u003e\u003cp\u003e\u003cstrong\u003eYes.\u003c\/strong\u003e Direct fit for the 2011-2015 Kia Optima \u003cstrong\u003eTheta II 2.4L GDI (G4KJ)\u003c\/strong\u003e. \u003cstrong\u003eExcludes 2016 models and all 2.0L Turbo engines.\u003c\/strong\u003e\u003c\/p\u003e\u003ch4\u003eWill this clear P0135, P0141, or P0420 codes?\u003c\/h4\u003e\u003cp\u003e\u003cstrong\u003eYes, when caused by faulty sensors.\u003c\/strong\u003e New \u003cstrong\u003e234-5029\u003c\/strong\u003e and \u003cstrong\u003e234-4238\u003c\/strong\u003e sensors resolve heater and response codes, though persistent \u003cstrong\u003eP0420\u003c\/strong\u003e requires catalytic converter inspection.\u003c\/p\u003e\u003ch4\u003eIs wiring modification needed for installation?\u003c\/h4\u003e\u003cp\u003e\u003cstrong\u003eNo.\u003c\/strong\u003e Both include OEM-style plugs for direct installation into factory bungs after clearing fault codes.\u003c\/p\u003e\u003ch3\u003eThe Kia Precision Standard\u003c\/h3\u003e\u003cp\u003eAccurate lambda feedback on the \u003cstrong\u003eTF\u003c\/strong\u003e platform protects catalytic efficiency and fuel economy, keeping your 2.4L Optima emissions-compliant and CEL-free.\u003c\/p\u003e","brand":"VelocityMax","offers":[{"title":"Default Title","offer_id":68119471456504,"sku":"DS-EO289YW3X","price":34.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0800\/1290\/2648\/files\/o2-oxygen-sensor-upstream-downstream-for-kia-optima-2011-2015-2-4l-1.jpg?v=1794722846","url":"https:\/\/performancechiptuning.com\/products\/o2-oxygen-sensor-upstream-downstream-for-kia-optima-2011-2015-2-4l","provider":"Performance Chip Tuning","version":"1.0","type":"link"}