O2 Oxygen Sensor Upstream Downstream for Infiniti EX35 FX35 (2011-2012) 3.5L

Direct-Fit Upstream and Downstream Oxygen Sensor Kit for 2011-2012 Infiniti EX35, FX35 (J50 / S51)

What it Does: The oxygen sensor kit restores closed-loop AFR monitoring and catalytic efficiency tracking on 2011-2012 EX35 and FX35 models to correct rough idling, erratic fueling, and check engine lights.

The Stock Infiniti EX35, FX35 Sensor Degradation

Exhaust heat and chemical contamination degrade factory zirconium and air-fuel ratio sensors over time on the high-revving VQ35HR platform. Over years of thermal cycling within the tight exhaust manifolds and post-cat bungs of the J50 and S51 chassis, internal heating elements burn out and ceramic thimbles foul with carbon soot, phosphorus, and oil blow-by. This leads to slow switching response times, false lean or rich signals, poor closed-loop fuel trims, reduced fuel economy, and persistent diagnostic trouble codes like P0130, P0138, or P0420.

The Engineering Solution

This four-piece replacement kit features dual upstream wideband air-fuel ratio sensors and dual downstream heated oxygen sensors calibrated to meet factory impedance and response curves. Constructed with laser-welded stainless steel bodies, corrosion-resistant dual protective filter covers, and integrated high-temperature pre-applied thread anti-seize, these sensors resist thermal shock and exhaust gas erosion. Factory-matched harness pigtails with OE-style locking connectors provide direct plug-and-play installation without wire splicing, matching OEM standards across 22693-1MR0A and 234-9135.

What's Included

• 2x Upstream Oxygen Sensors (Air-Fuel Ratio Sensors)
• 2x Downstream Oxygen Sensors (Heated Catalyst Monitors)

Technical Specifications

Compatibility

• 2011-2012 Infiniti EX35 Base & Journey 3.5L V6 (J50)
• 2011-2012 Infiniti FX35 Base 3.5L V6 (S51)

Frequently Asked Questions & Fitment Warnings

Does this fit the J50 and S51 EX35 and FX35?

Yes, this is a direct fit for the 2011-2012 Infiniti EX35 and FX35 equipped with the 3.5L VQ35HR engine. It is not compatible with earlier DE engine variants or FX50 5.0L V8 applications.

Do these sensors require wire cutting or universal splice kits during installation?

No, all four sensors feature OE-spec wire lengths and terminal pinouts for a direct bolt-in and plug-in replacement.

The Infiniti Precision Caliber

Engineered for the tight air-fuel tolerances of high-output Japanese V6 powertrains, this four-sensor kit maintains target lambda values to preserve throttle response, optimize combustion, and prevent pre-catalytic converter damage.