Oxygen Sensors for Infiniti FX35 G35 (2003-2006) 3.5L Downstream

Direct-Fit Downstream Oxygen Sensor Set for 2003-2006 Infiniti FX35, G35

What it Does: The Downstream Oxygen Sensor Set monitors catalytic converter efficiency and post-combustion exhaust gas on the 2003-2006 Infiniti FX35 and G35 to maintain precise closed-loop ECM fuel trimming and prevent false emissions-related trouble codes.

The Stock Infiniti FX35, G35 Sensor Degradation Failure Points

Factory secondary oxygen sensors on high-mileage VQ35DE engines suffer from prolonged exposure to thermal cycling, exhaust gas condensation, and carbon build-up. Over time, the internal ceramic electrolyte element loses its sensitivity, and the internal heater circuit deteriorates. This degradation leads to sluggish voltage response, signal clipping, and recurrent check engine lights (such as P0420, P0430, P0138, or P0158). Worn downstream sensors also prevent the engine control module from accurately verifying catalyst efficiency, skewing long-term trim calculations and causing rough idle conditions.

The Engineering Solution

This 2-piece downstream sensor set is engineered to match factory electrical resistance and output voltage parameters precisely. Built with high-grade 304 stainless steel housings and porous PTFE filters, each sensor resists thermal shock, road debris, and corrosive exhaust contaminants. Fast-activating planar heater circuits rapidly reach operating temperature to establish closed-loop monitoring immediately after cold starts. Pre-terminated, OEM-style weather-pack harness connectors and pre-treated threads ensure straightforward installation without splicing or harness repinning.

Technical Specifications

Compatibility

• 2003-2006 Infiniti FX35 Base Sport Utility 3.5L V6 (S50) – Downstream (Bank 1 & Bank 2 Sensor 2)
• 2003-2006 Infiniti G35 Sedan 3.5L V6 (V35) – Downstream (Bank 1 & Bank 2 Sensor 2)
• 2003-2006 Infiniti G35 Coupe 3.5L V6 (V35) – Downstream (Bank 1 & Bank 2 Sensor 2)

Frequently Asked Questions

Does this fit the V35 and S50 FX35, G35?
Yes, this is a direct fit for the 2003-2006 Infiniti FX35 and G35 equipped with the VQ35DE 3.5L engine in the downstream (post-catalytic converter) positions.

Can these downstream sensors be installed in the upstream manifold positions?
No, downstream units are specifically calibrated for post-catalytic monitoring and utilize application-specific lead lengths and connectors distinct from the upstream air-fuel ratio sensors.

The Infiniti Performance Standard

Designed to maintain the refined power and crisp throttle response expected of the Nissan/Infiniti VQ platform, these sensors withstand sustained high-RPM operation and high exhaust temperatures without dropping signal continuity or throwing false emissions flags.