Denso 234-4821 Oxygen Sensor - Downstream or Upstream

Denso OE Style Oxygen Sensor 234-4821

Denso 234-4821 is an OE Style heated oxygen sensor built for specific-fit replacement on select Buick, Chevrolet, Cadillac, Saab, Pontiac, and Saturn applications. It is engineered for direct replacement service with the correct connector, threaded mounting, and harness length for the listed downstream and upstream positions.

Key Features

• OE Style replacement oxygen sensor for specific-fit applications
• Heated sensor design for faster operating response
• 4-wire configuration with female connector
• Threaded mounting with 0.708 in. thread diameter
• Wiring harness length: 15.79 in.
• Built to match the listed upstream and downstream locations

OE Style Construction

Denso’s OE Style line is built and tested to OE standards for exact replacement fit and consistent sensor performance. This oxygen sensor uses Denso’s aluminum oxide trap layer to help protect the ceramic element from silicone and lead contamination, supporting stable engine management, fuel control, and long service life. The Denso 234-4821 is a direct-fit solution for drivers and technicians who need the correct sensor the first time.

This part cross-references Bosch (e.g., 16349, 16378) for the same application.

Vehicle Fitment

• Fits 2019-2021 Buick Encore, downstream.
• Fits 2018-2021 Chevrolet Trax, downstream.
• Fits 2013-2018 Buick Encore, downstream.
• Fits 2018 Chevrolet Express 2500, downstream; LUV engine.
• Fits 2015-2017 Chevrolet Trax, downstream.
• Fits 2010-2011 Cadillac SRX, upstream.
• Fits 2010-2011 Cadillac SRX, downstream.
• Fits 2011 Saab 9-4X, upstream.
• Fits 2011 Saab 9-4X, downstream.
• Fits 2010-2011 Saab 9-5, upstream.
• Fits 2008-2009 Pontiac G8, downstream.
• Fits 2006-2009 Saab 9-3, downstream.
• Fits 2004 Buick Rendezvous, downstream.
• Fits 2003-2004 Cadillac CTS, upstream.
• Fits 2003-2004 Cadillac CTS, downstream.
• Fits 2002-2003 Saturn Vue, upstream.
• Fits 2002-2003 Saturn Vue, downstream.

Common Issues This Sensor Can Address

• Fault codes related to oxygen sensor response or circuit performance
• Rough idle or inconsistent air-fuel feedback from a worn sensor
• Reduced fuel economy caused by inaccurate exhaust oxygen readings
• Emissions test failures tied to aging upstream or downstream sensors
• Check engine light concerns on Buick Encore, Chevrolet Trax, Cadillac SRX, and related applications

Installation Notes

Confirm the vehicle position before ordering, since this part is listed for both upstream and downstream locations depending on application. Match the connector style, wire count, and threaded mounting dimensions to the original sensor. For best results, inspect the exhaust threads and wiring routing before installation, and verify the part number 234-4821 against the vehicle’s exact engine and sensor location.

Quality Assurance

Denso manufactures this OE Style oxygen sensor to strict OE standards and tests each design for direct-fit replacement accuracy. The sensor’s contamination-resistant trap layer is part of Denso’s durability-focused construction, supporting dependable operation in demanding exhaust environments.