Denso 234-3081 Oxygen Sensor - Upstream

OE-Style Oxygen Sensor for Mercedes-Benz

The Denso 234-3081 oxygen sensor is a specific-fit, heated replacement built to OE-style dimensions for direct service on select Mercedes-Benz applications. It is engineered for accurate exhaust feedback, stable engine management, and a first-time fit on upstream positions.

Key Features

• Heated oxygen sensor for faster operating response
• Specific-fit design for direct replacement service
• Threaded mounting type with 0.708 in. thread diameter
• 3-wire configuration with male/female connector
• 38.19 in. wiring harness length for application-specific routing
• OE Style construction from Denso

Product Details

Denso OE Style oxygen sensors are manufactured and tested to OE standards for precise replacement fit and dependable signal performance. Part number 234-3081 uses a heated, threaded design and application-specific wiring to match the original sensor layout on select Mercedes-Benz models, including 1986-1992 Mercedes-Benz 300E, upstream, and 1986-1991 Mercedes-Benz 420SEL, upstream. This part number 234-3081 also applies to other upstream Mercedes-Benz fitments in the same OE-style range, including 560SEL and 560SEC applications.

The OE Style line focuses on exact replacement geometry and sensor construction. Denso also uses an aluminum oxide trap layer to help protect the ceramic element from silicone and lead contamination, supporting consistent exhaust monitoring and long service life. This part cross-references Bosch (e.g., 13925, 13926) for the same application.

What This Sensor Helps Address

• Check engine light caused by oxygen sensor signal faults
• Rough idle or unstable air-fuel control from a worn upstream sensor
• Reduced fuel economy from inaccurate exhaust feedback
• Slow sensor response during closed-loop operation
• Replacement needs on Mercedes-Benz 300E, 420SEL, 560SEL, and related upstream applications

Installation Notes and Tips

Verify the upstream position, connector style, wire count, and thread size before installation. Match the harness routing to the original sensor path and inspect the exhaust bung threads for damage or contamination. For best results, confirm the vehicle application by year, make, model, and position before ordering Denso 234-3081.

Quality Assurance

Denso manufactures and tests this oxygen sensor to strict OE standards for fit and performance. The OE Style design is built for direct replacement service, and the contamination-resistant sensor construction supports reliable operation in demanding exhaust environments.