Denso 234-4612 Oxygen Sensor - Downstream or Downstream Right

OE-Style Oxygen Sensor for Mazda and Kia

Denso 234-4612 is an OE-style heated oxygen sensor built for specific-fit replacement on select Mazda and Kia applications. It is engineered for direct replacement service on downstream positions, including Mazda Millenia and Mazda Protege coverage, with the correct connector, threaded mounting, and harness length for a first-time fit.

This sensor is part of Denso’s OE Style line, which focuses on exact replacement geometry and factory-style performance. The design uses an aluminum oxide trap layer to help protect the ceramic element from silicone and lead contamination, supporting stable engine operation and consistent fuel control.

Key Features

• Part number: 234-4612
• Heated oxygen sensor for specific-fit applications
• 4-wire design with female connector
• Threaded mounting type with 0.708 in. thread diameter
• Wiring harness length: 32.28 in.
• OE-style replacement for downstream sensor locations
• Built to strict OE standards for fit and function

Detailed Description

Denso 234-4612 is a direct-fit oxygen sensor for emissions control service where accurate exhaust feedback is required. It is listed for 1995-2002 Mazda Millenia, downstream right; 1995-1998 Mazda Protege, downstream; 1996-1997 Kia Sephia, downstream; and 1996 Mazda MX-3, downstream. If you are searching for a downstream oxygen sensor for a Mazda Millenia or Mazda Protege replacement, this OE-style sensor is built to match the original installation points and electrical layout. This part cross-references Bosch 13581 and NTK 22001 for the same application.

Common Issues It Can Help Address

• Check engine light related to oxygen sensor performance
• Incorrect air-fuel mixture readings from a worn downstream sensor
• Reduced fuel economy caused by slow sensor response
• Emissions test failures tied to aging exhaust feedback components
• Rougher engine operation from contaminated or degraded sensor elements

Installation Notes and Tips

Confirm the vehicle year, make, model, and sensor position before ordering. This is a specific-fit, threaded heated oxygen sensor with a female connector, so connector style and harness routing should be matched to the original part. For best results, inspect the exhaust threads and wiring path before installation, and verify downstream right or downstream placement as listed for the application.

Quality Assurance

Denso manufactures and tests this oxygen sensor to OE standards for replacement accuracy and consistent performance. The OE Style line is built for exact fitment and includes contamination-resistant sensor protection to support long service life in demanding exhaust conditions.