NTK 25081 Oxygen Sensor - Upstream

Direct Fit Oxygen Sensor for Mercedes-Benz

NTK 25081 is a direct fit oxygen sensor built for specific Mercedes-Benz applications. It uses a heated, threaded design with a 3-wire configuration and a 30-inch harness length for OE-style replacement on the correct upstream location.

Key Features

• Direct fit oxygen sensor for specific applications
• Heated sensor design for faster operating response
• 3-wire configuration with threaded mounting
• 30-inch wiring harness length
• 18 mm thread diameter

Detailed Description

NTK 25081 is part of the Direct Fit Oxygen Sensor line, engineered for specific import and domestic applications with OE-style fit, form, and function. NTK is known for oxygen sensor manufacturing and uses ceramic technology developed from raw material through finished product control. This sensor is listed for upstream use on Mercedes-Benz 300E, 300CE, 300TE, 300SE, 300SEL, 260E, 560SL, and 450SLC applications, with fitment notes that include Bank 1 Sensor 1 coverage on several models. This part cross-references Bosch (e.g., 13146, 13925) for the same application.

Common Issues This Part May Address

• Faulty oxygen sensor signal affecting air-fuel ratio control
• Check engine light related to upstream sensor performance
• Slow sensor response during closed-loop operation
• Incorrect fuel mixture caused by aging sensor output
• Driveability issues tied to worn sensor elements

Installation Notes and Tips

Confirm the vehicle’s upstream sensor location, connector style, and thread size before installation. The fitment data for NTK 25081 includes Mercedes-Benz applications with Bank 1 Sensor 1 notes on several models, so match the exact year, model, and position before ordering. Use the listed harness length and threaded mounting details to verify routing and sensor placement.

Quality Assurance

NTK states that its oxygen sensors are extensively tested during manufacturing to meet or exceed OE specifications. The brand also supplies original equipment oxygen sensors and supports broad application coverage through its Direct Fit Oxygen Sensor line.