NTK 25578 Oxygen Sensor - Upstream

Direct-Fit Oxygen Sensor

NTK 25578 is a direct-fit heated oxygen sensor built for specific applications and threaded mounting. It uses a 4-wire design with a 17.75-inch harness and an 18 mm thread diameter for a precise replacement path.

Compatible with select Hyundai and Mitsubishi applications, this NTK oxygen sensor is part of the Direct Fit Oxygen Sensor line. The design focuses on OE-style fit, form, and function for import and domestic coverage.

Key Features

• Heated oxygen sensor for specific-fit applications
• 4-wire configuration for signal and heater circuit operation
• Threaded mounting with 18 mm thread diameter
• 17.75-inch wiring harness length
• NTK 25578 direct-fit replacement

Detailed Description

NTK 25578 is engineered as a direct-fit oxygen sensor for upstream applications where accurate air-fuel feedback is required. The heated design helps the sensor reach operating temperature quickly, while the threaded body and specific-fit configuration support straightforward replacement in the correct application. This part number is listed for 1991-1993 Mitsubishi Galant, 1992-1993 Hyundai Sonata, and 1992-1993 Hyundai Elantra applications, including upstream Bank 1 Sensor 1 and B1S1 positions where noted. If you are sourcing an oxygen sensor for a Hyundai Elantra, Hyundai Sonata, or Mitsubishi Galant, NTK 25578 provides an OE-style replacement path.

NTK is known for oxygen sensor manufacturing and OE application coverage. The brand’s Direct Fit Oxygen Sensor line is built to streamline replacement selection while maintaining fit and function expectations for the listed applications. This part cross-references DENSO Auto Parts 234-4644 for the same application.

What It Helps Address

• Faulty oxygen sensor readings
• Check engine light concerns related to sensor performance
• Air-fuel ratio feedback issues
• Slow sensor warm-up from a failing heater circuit
• Replacement needs for upstream sensor locations

Installation Notes and Quality

Verify the vehicle’s year, make, model, and sensor location before installation. Match the connector, thread size, wire count, and harness length to the original part for proper fitment. NTK states that these oxygen sensors are extensively tested during manufacturing to meet or exceed OE specifications.

NTK 25578 is backed by the brand’s OE-focused manufacturing approach and application coverage for import and domestic vehicles.