O2 Oxygen Sensor Upstream Downstream for Infiniti G35 FX35 (2003-2004) 3.5L

Direct-Fit Upstream & Downstream O2 Sensor Kit for 2003-2004 Infiniti G35,FX35 (V35, S50)

What it Does: This 4-piece O2 sensor kit monitors exhaust oxygen concentration and catalyst efficiency on 2003-2004 Infiniti G35 (V35) and FX35 (S50) VQ35DE 3.5L models.

The Stock Infiniti G35,FX35 Oxygen Sensor Failure

On aging V35 and S50 platforms equipped with the VQ35DE 3.5L V6, OEM oxygen sensors fail from thermal fatigue, internal heater burnout, and zirconia contamination. As sensing elements degrade, voltage switching slows down, skewing fuel trims across Bank 1 and Bank 2. Faulty heater circuits or slow response trigger P0130, P0150, P0031, and P0051 codes, forcing rich open-loop operation and reduced fuel economy.

Common Symptoms of a Failing OEM Oxygen Sensor

• Check Engine Light & DTCs: Triggers P0130, P0150, P0138, P0158, or P0031/P0051 when voltage stalls or heater circuits open.
• Rich Exhaust & Rough Idle: Delayed sensor switching forces overly rich fuel compensation, fouling spark plugs.
• Failed Emissions: Inaccurate downstream catalyst readings trigger P0420/P0430 codes and drop MPG.

The Direct-Fit Zirconia O2 Sensor Solution

Replacing all four sensors as a matched set restores balanced Bank 1 and Bank 2 closed-loop fuel control across upstream and downstream positions. Each direct-fit sensor uses a fast-acting planar zirconia element, laser-welded stainless housing, and PTFE-insulated wiring to resist exhaust heat soak and moisture. Factory-spec OEM connectors install directly into stock V35 and S50 bungs with zero splicing, replacing 234-4302, 234-4308, 234-4312, and 1A250-24403.

What's Included

• 2 Upstream Oxygen Sensors
• 2 Downstream Oxygen Sensors

Technical Specifications

Compatibility

• Infiniti G35 2003-2004 3.5L (V35)
• Infiniti FX35 2003-2004 3.5L (S50)

Frequently Asked Questions & Fitment Warnings

Does this fit the V35/S50 G35,FX35?

Yes. This is a direct fit for 2003-2004 Infiniti G35 (V35) and FX35 (S50) models equipped with the VQ35DE 3.5L V6 engine. Excludes 2005+ models and FX45 4.5L V8 trims; confirm engine before ordering.

Will this clear O2 and heater circuit codes?

Yes. Replacing all four sensors resolves slow-switching and heater circuit faults like P0031, P0051, P0130, and P0150 when exhaust leaks and harness damage are absent.

Is cutting or splicing required for installation?

No. Factory-spec OEM connectors plug straight into stock harnesses; treat seized bungs with penetrant beforehand and torque using an O2 sensor socket.

The Infiniti Precision Standard

Built for VQ35DE platforms, this 4-piece sensor kit restores factory ECM precision, crisp throttle response, and CEL-free emissions compliance across both exhaust banks.