{"product_id":"o2-oxygen-sensor-upstream-downstream-for-nissan-350z-2003-2004-3-5l","title":"O2 Oxygen Sensor Upstream Downstream for Nissan 350Z (2003-2004) 3.5L","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 2003-2004 Nissan 350Z (Z33)\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eWhat it Does:\u003c\/strong\u003e This 4-piece upstream and downstream O2 oxygen sensor kit monitors pre- and post-catalytic converter exhaust oxygen levels on the 2003-2004 Nissan 350Z (\u003cstrong\u003eZ33\u003c\/strong\u003e) \u003cstrong\u003eVQ35DE 3.5L V6\u003c\/strong\u003e to regulate closed-loop air-fuel ratios and verify catalyst efficiency.\u003c\/p\u003e\u003ch3\u003eThe Stock Nissan 350Z O2 Sensor Failure\u003c\/h3\u003e\u003cp\u003eFactory oxygen sensors on the \u003cstrong\u003eZ33\u003c\/strong\u003e chassis equipped with the \u003cstrong\u003eVQ35DE 3.5L V6\u003c\/strong\u003e endure severe thermal cycling, exhaust carbon buildup, and oil vapor contamination inside the dual-bank exhaust manifolds and mid-pipes. Over time, internal ceramic zirconia sensing elements glaze over or fracture from heat soak, while internal heater circuits burn out from resistance spikes. Once response latency increases, the ECM loses accurate stoichiometric fuel trim control, triggering \u003cstrong\u003eP0135\u003c\/strong\u003e, \u003cstrong\u003eP0155\u003c\/strong\u003e, or lean\/rich fuel trim faults like \u003cstrong\u003eP0171\u003c\/strong\u003e and \u003cstrong\u003eP0174\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 \/ O2 \u0026amp; Fuel Trim DTCs:\u003c\/strong\u003e Triggered fault codes such as \u003cstrong\u003eP0130\u003c\/strong\u003e, \u003cstrong\u003eP0135\u003c\/strong\u003e, \u003cstrong\u003eP0155\u003c\/strong\u003e, or \u003cstrong\u003eP0171\/P0174\u003c\/strong\u003e caused by open heater circuits or sluggish sensor voltage switching.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eErratic Closed-Loop Fueling \u0026amp; Poor Economy:\u003c\/strong\u003e Delayed upstream sensor feedback forces the ECM into rich open-loop default maps, fouling spark plugs and increasing fuel consumption.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFailed Emissions Inspection \u0026amp; Rough Idle:\u003c\/strong\u003e Compromised downstream monitoring and skewed Bank 1\/Bank 2 air-fuel balance cause inconsistent idle quality and elevated tailpipe emissions.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eThe Direct-Fit 4-Piece Oxygen Sensor Solution\u003c\/h3\u003e\u003cp\u003eReplacing all four sensors simultaneously restores synchronized Bank 1 and Bank 2 voltage feedback across the \u003cstrong\u003eZ33\u003c\/strong\u003e dual-exhaust architecture. Each sensor utilizes a corrosion-resistant stainless steel housing, high-temperature internal heater element, and OE-grade zirconia sensing core engineered to withstand exhaust thermal shock. Pre-terminated factory-style harnesses match OE lengths and connector keying for direct plug-and-play replacement of part numbers \u003cstrong\u003e234-4302\u003c\/strong\u003e, \u003cstrong\u003e234-4308\u003c\/strong\u003e, \u003cstrong\u003e234-4312\u003c\/strong\u003e, and \u003cstrong\u003e1A250-24403\u003c\/strong\u003e without wire splicing.\u003c\/p\u003e\u003ch3\u003eWhat's Included\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e2x Upstream Oxygen Sensors\u003c\/li\u003e\n\u003cli\u003e2x Downstream Oxygen Sensors\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;\"\u003e2003-2004 Nissan 350Z\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;\"\u003eVQ35DE 3.5L V6 \/ Z33\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 Engine Output\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e287 hp \/ 274 lb-ft\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;\"\u003e234-4302, 234-4308, 234-4312, 1A250-24403\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003c\/div\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e2003 Nissan 350Z 3.5L\u003c\/li\u003e\n\u003cli\u003e2004 Nissan 350Z 3.5L\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions \u0026amp; Fitment Warnings\u003c\/h3\u003e\u003ch4\u003eDoes this fit the Z33 350Z?\u003c\/h4\u003e\u003cp\u003e\u003cstrong\u003eYes.\u003c\/strong\u003e This is a direct fit for the 2003-2004 Nissan 350Z equipped with the \u003cstrong\u003eVQ35DE 3.5L V6\u003c\/strong\u003e engine. \u003cstrong\u003eConfirm your 3.5L engine before ordering; this kit does not fit 2005-2009 Nissan 350Z models or later VQ35HR dual-intake engines.\u003c\/strong\u003e\u003c\/p\u003e\u003ch4\u003eWill this clear P0135, P0155, or P0171 codes, and are all four sensors included?\u003c\/h4\u003e\u003cp\u003e\u003cstrong\u003eYes.\u003c\/strong\u003e This matched 4-piece kit includes both Bank 1 and Bank 2 upstream sensors and both downstream sensors to resolve O2 heater circuit faults like \u003cstrong\u003eP0135\u003c\/strong\u003e\/\u003cstrong\u003eP0155\u003c\/strong\u003e and slow-response fuel trim codes like \u003cstrong\u003eP0171\u003c\/strong\u003e after clearing ECM memory, provided no exhaust leaks or wiring harness damage exist.\u003c\/p\u003e\u003ch4\u003eIs wire splicing required for installation?\u003c\/h4\u003e\u003cp\u003e\u003cstrong\u003eNo.\u003c\/strong\u003e All four direct-fit sensors include factory-keyed electrical connectors and OE harness lengths for plug-and-play installation into existing exhaust bungs; clean bung threads with a thread chaser before torquing and avoid getting anti-seize on the sensor tip.\u003c\/p\u003e\u003ch3\u003eThe Nissan Performance Standard\u003c\/h3\u003e\u003cp\u003eAccurate exhaust oxygen feedback is essential for maintaining combustion efficiency, catalyst health, and crisp throttle response on the \u003cstrong\u003eZ33\u003c\/strong\u003e platform. Replacing all four sensors as a matched set keeps Bank 1 and Bank 2 fueling balanced under aggressive street and high-RPM driving loads.\u003c\/p\u003e","brand":"VelocityMax","offers":[{"title":"Default Title","offer_id":68107276452088,"sku":"DS-EPEV2UZ2J","price":92.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0800\/1290\/2648\/files\/o2-oxygen-sensor-upstream-downstream-for-nissan-350z-2003-2004-3-5l-1.jpg?v=1794681817","url":"https:\/\/performancechiptuning.com\/products\/o2-oxygen-sensor-upstream-downstream-for-nissan-350z-2003-2004-3-5l","provider":"Performance Chip Tuning","version":"1.0","type":"link"}