Denso 234-5039 Air / Fuel Ratio Sensor - Upstream

Denso OE Style Air/Fuel Ratio Sensor

Denso OE Style Air/Fuel Ratio Sensor Part Number 234-5039 is a specific-fit, heated sensor built for precise replacement in emission control systems. It is engineered to match OE standards for accurate signal response and a first-time fit on select Ford, Mazda, and Mercury applications.

The OE Style line focuses on direct replacement fitment and consistent connector and thread specifications, making 234-5039 a practical choice for drivers servicing upstream air/fuel ratio sensor faults on vehicles such as the Ford Escape and Ford Fusion.

Key Features

• Heated air/fuel ratio sensor for upstream placement
• Specific fit design for direct replacement applications
• 5-wire configuration with male connector
• Wiring harness length: 16.61
• Thread diameter: 0.711
• Built and tested to OE standards for replacement accuracy

Detailed Product Information

Denso 234-5039 is an OE Style air/fuel ratio sensor designed for precise air-fuel monitoring in the exhaust stream. As a heated sensor, it reaches operating temperature quickly to support stable feedback to the engine management system. This helps maintain proper fuel control on vehicles that rely on upstream sensor input, including 2010-2013 Ford Escape, 2010-2012 Ford Fusion, 2010-2011 Mazda Tribute, and 2010-2011 Mercury Mariner and Mercury Milan.

This part cross-references Bosch 18124 and Motorcraft DY997 for the same application. The Denso OE Style line is built around exact replacement dimensions and connector fitment, which is important when replacing a sensor such as 234-5039 on Ford Escape or Ford Fusion applications.

What This Sensor Helps Address

• Check engine light related to upstream air/fuel ratio sensor faults
• Rough idle caused by inaccurate exhaust oxygen feedback
• Fuel trim issues from delayed or inconsistent sensor response
• Emissions test failures tied to sensor performance problems
• Driveability concerns on Ford, Mazda, and Mercury vehicles with upstream sensor codes

Installation Notes and Tips

Verify the connector style, wire count, and thread diameter before installation. This sensor is a specific-fit upstream unit, so confirm the vehicle application and sensor position match the listing before replacement. Inspect the harness routing and connector condition during service to help ensure a secure electrical connection.

Fits 2010-2013 Ford Escape, Upstream. Fits 2010-2012 Ford Fusion, Upstream. Fits 2010-2011 Mazda Tribute, Upstream. Fits 2010-2011 Mercury Mariner, Upstream. Fits 2010-2011 Mercury Milan, Upstream.

Quality Assurance

Denso manufactures and tests this sensor to OE standards for replacement accuracy and consistent fit. The OE Style product line is intended to deliver the correct part and the correct fit for the listed applications.