Denso 234-4161 Oxygen Sensor - Downstream, Downstream Left or Upstream

Denso OE Style Oxygen Sensor 234-4161

Denso 234-4161 is an OE Style heated oxygen sensor built for exact replacement and specific-fit applications. It is engineered for Toyota Sequoia, Tundra, 4Runner, Tacoma, and T100 applications where accurate exhaust feedback is needed for proper fuel control and emissions performance.

Key Features

• Heated oxygen sensor with a 4-wire design
• Specific fit for direct application matching
• Wiring harness length: 15.35
• OE Style construction for factory-style replacement
• Built with Denso’s aluminum oxide trap layer to help protect the sensing element from silicone and lead contamination

Product Details

Denso OE Style sensors are manufactured and tested to OE standards for precise fit and consistent signal output. Part number 234-4161 is designed as a direct replacement oxygen sensor for downstream and upstream locations across select Toyota models, including Toyota Sequoia, Toyota Tundra, Toyota 4Runner, Toyota Tacoma, and Toyota T100. This part cross-references Bosch 13051 and NTK 24554 for the same application.

The OE-style design supports accurate air-fuel ratio monitoring, helping the engine control system maintain proper combustion and emissions operation. The heated sensor design helps it reach operating temperature faster, which is important for stable feedback during cold starts and normal driving.

Vehicle Fitment

• Fits 2001-2004 Toyota Sequoia, downstream.
• Fits 2000-2004 Toyota Tundra, downstream.
• Fits 2003-2004 Toyota Tundra, downstream left.
• Fits 1999-2000 Toyota 4Runner, upstream, excluding California.
• Fits 2000 Toyota Tacoma, upstream, excluding California.
• Fits 2000 Toyota Tundra, upstream.
• Fits 1995-1999 Toyota Tacoma, upstream.
• Fits 1996-1998 Toyota 4Runner, upstream.
• Fits 1995-1998 Toyota T100, downstream.
• Fits 1994-1995 Toyota 4Runner, downstream, California exempt parts can be used on pollution controlled vehicles in California.

Common Issues This Part Can Address

• Check engine light related to oxygen sensor performance
• Incorrect fuel mixture readings from a worn sensor
• Reduced fuel economy caused by slow or inaccurate exhaust feedback
• Rough idle or drivability concerns tied to sensor degradation
• Emissions test failures caused by a faulty upstream or downstream sensor

Installation Notes and Tips

Confirm the sensor position before ordering, since this part is used in upstream, downstream, and downstream left locations depending on the vehicle. Verify connector style, wire count, and harness length against the original sensor before installation. For Toyota 4Runner, Tacoma, and Tundra applications, review the fitment notes carefully, especially California exclusions and California exempt coverage where listed.

Quality Assurance

Denso manufactures and tests this OE Style oxygen sensor to strict original-equipment standards for fit and performance. The sensor’s protective trap layer is designed to help reduce contamination-related wear and support longer service life in demanding exhaust environments.