Denso 234-4146 Oxygen Sensor - Upstream

Denso OE Style Oxygen Sensor 234-4146

The Denso 234-4146 is a specific-fit heated oxygen sensor built to OE-style dimensions for direct replacement on select Mazda applications. It is engineered for accurate exhaust feedback, stable engine management, and a first-time fit on the listed vehicle.

Compatible with 1999-2000 Mazda Protege upstream applications excluding California, this sensor is a direct-fit choice for drivers replacing a worn or slow-responding oxygen sensor. The Denso OE Style line focuses on exact replacement fitment and OE-level construction for dependable service.

Key Features

• Specific-fit heated oxygen sensor for direct replacement
• OE Style design for exact replacement dimensions
• 4-wire configuration with female connector
• Threaded mounting type with 0.708 in. thread diameter
• 14.96 in. wiring harness length
• Built with Denso’s aluminum oxide trap layer to help protect the ceramic element from silicone and lead contamination
• Fits 1999-2000 Mazda Protege upstream, excluding California

Detailed Description

Denso 234-4146 is part of Denso’s OE Style sensor line, which is built and tested to OE standards for accurate replacement fitment and consistent operation. This heated oxygen sensor is designed for the upstream location on the 1999-2000 Mazda Protege, excluding California emissions applications, and uses a threaded mount with a 4-wire female connector for a direct installation profile. The Denso 234-4146 is a practical replacement when the original sensor has aged, slowed response, or triggered drivability and emissions concerns.

This part cross-references Bosch 13886 and NTK 22531 for the same application.

What It Helps Address

• Check engine light related to oxygen sensor performance
• Rough idle or inconsistent air-fuel control
• Reduced fuel economy from inaccurate exhaust feedback
• Slow sensor response during closed-loop operation
• Emissions test failures tied to upstream sensor issues

Installation Notes and Tips

Confirm the upstream position and verify that your Mazda Protege is not a California emissions application before ordering. Match the connector style, wire count, and thread size to the original sensor before installation. Inspect the harness routing and exhaust threads during replacement to help ensure proper seating and signal performance.

Quality Assurance

Denso manufactures this OE Style oxygen sensor to strict OE standards and tests it for replacement accuracy and fit. The sensor’s protective trap layer is designed to help shield the ceramic element from contamination, supporting long-term performance in normal exhaust conditions.