O2 Oxygen Sensor Upstream Downstream for Toyota Sequoia (2001-2004) 4.7L

Direct-Fit Upstream and Downstream Oxygen Sensor Kit for 2001-2004 Toyota Sequoia (UCK35/UCK45)

What it Does: The complete 4-piece O2 oxygen sensor kit replaces degraded factory sensors on the 2001-2004 Toyota Sequoia to restore closed-loop fuel trim management and eliminate diagnostic trouble codes.

The Stock Toyota Sequoia Sensor Degradation Problem

Over extended heat cycles and high mileage, factory zirconium dioxide oxygen sensors on the Toyota Sequoia UCK35/UCK45 suffer from thermal fatigue, silica poisoning, and carbon encrustation. Exhaust gas soot coats the porous ceramic thimble, severely lagging response times between stoichiometric lean and rich transitions. This sensor sluggishness forces the 2UZ-FE engine control module (ECM) into conservative open-loop or rich-bias operation, causing elevated fuel consumption, catalytic converter overheating, and persistent P0135, P0141, P0171, or P0420 fault codes.

The Engineering Solution

This comprehensive upstream and downstream replacement kit utilizes premium planar zirconia sensing elements with fast-acting integrated ceramic heaters to achieve rapid operating temperature activation. Built with dual-laser-welded stainless steel sub-assemblies and PTFE-shielded harness leads, these direct-fit sensors resist moisture intrusion and thermal degradation from radiant exhaust header heat. Calibrated output voltages accurately communicate real-time lambda readings to the ECM, stabilizing short-term and long-term fuel trims (STFT/LTFT) while protecting emissions equipment. Direct-fit pre-wired weatherproof connectors match OEM pinouts, eliminating the need for wire splicing or custom pinning.

What's Included

• 2X 234-4169 Upstream Oxygen Sensors
• 2X 234-4161 Downstream Oxygen Sensors

Technical Specifications

Compatibility

• 2001 Toyota Sequoia SR5 / Limited 4.7L V8 (2WD / 4WD)
• 2002 Toyota Sequoia SR5 / Limited 4.7L V8 (2WD / 4WD)
• 2003 Toyota Sequoia SR5 / Limited 4.7L V8 (2WD / 4WD)
• 2004 Toyota Sequoia SR5 / Limited 4.7L V8 (2WD / 4WD)

Frequently Asked Questions & Fitment Warnings

Does this fit the UCK35/UCK45 Sequoia?

Yes, this is a direct fit for the 2001-2004 Toyota Sequoia equipped with the 2UZ-FE 4.7L engine. Confirm your vehicle has the 4.7L V8 naturally aspirated engine prior to purchase, as this kit does not fit 2005+ VVTi engine configurations or V6 models.

Do these sensors require wire cutting or splicing during installation?

No, these direct-fit sensors come pre-terminated with factory-style OE harness connectors and wire lengths for straightforward bolt-on replacement.

The Toyota Truck Caliber

Engineered to endure the rigorous thermal demands of heavy towing, hauling, and off-road trail conditions, these oxygen sensors restore factory combustion precision and long-haul reliability to your Toyota truck platform.