NTK 25177 Oxygen Sensor - Downstream

Direct-Fit Oxygen Sensor Overview

The NTK 25177 is a direct-fit heated oxygen sensor built for specific applications and engineered for OE-level fit, form, and function. It is a threaded sensor with a 4-wire design and a 12-inch harness for a clean replacement on the exhaust system.

Fits 2004-2005 Kia Rio, downstream. This NTK oxygen sensor is part of the Direct Fit Oxygen Sensor line, which focuses on streamlined coverage and application-specific replacement parts.

Key Features

• Heated oxygen sensor with specific-fit application coverage
• 4-wire design for proper signal and heater circuit operation
• 12-inch wiring harness length for installation flexibility
• Threaded mounting type with 18 mm thread diameter
• NTK 25177 direct-fit replacement for emission control service

Detailed Description

NTK 25177 is an emission control oxygen sensor designed for direct replacement in the exhaust stream. As a downstream sensor for the 2004-2005 Kia Rio, it helps monitor exhaust oxygen content after the catalytic converter so the engine management system can maintain accurate fuel control and emissions monitoring. The heated design supports faster sensor operation, while the threaded construction and specific-fit configuration simplify matching the original application. The NTK 25177 is also cross-referenced to Bosch 15648 and Delphi ES10856 for the same application.

What It Helps Address

• Check engine light related to oxygen sensor performance
• Incorrect air-fuel mixture feedback from a worn sensor
• Slow sensor response during closed-loop operation
• Emissions test failures caused by a faulty downstream sensor
• Exhaust monitoring issues on the Kia Rio

Installation Notes and Tips

Confirm the downstream location and connector match before installation. Use the 18 mm threaded mounting point and verify the 12-inch harness reaches the original routing path without strain. For best results, inspect the exhaust threads and wiring condition before installing the NTK 25177.

Quality Assurance

NTK is part of the NGK family of products and is a major original equipment oxygen sensor supplier. Each sensor is extensively tested during manufacturing to meet or exceed OE specifications for quality and reliability.