NTK 22521 Oxygen Sensor - Downstream

Direct Fit Oxygen Sensor

NTK 22521 is a direct fit heated oxygen sensor built for specific applications with threaded mounting and a 4-wire design. It is engineered for downstream use and matches the original equipment style needed for accurate exhaust feedback.

Compatible with 1996-1997 Mercury Villager, downstream, and 1996-1997 Nissan Quest, downstream. This NTK oxygen sensor is part of the Direct Fit Oxygen Sensor line, which focuses on streamlined coverage and OE-style application matching.

Key Features

• Heated oxygen sensor for faster operating response.
• Specific-fit design for direct application matching.
• Threaded mounting with 18 mm thread diameter.
• 50.75 in. wiring harness length for proper routing.
• 4-wire configuration for the listed applications.

Detailed Description

NTK 22521 is an emission control oxygen sensor developed for downstream placement in the listed Mercury and Nissan applications. As part of NTK's Direct Fit Oxygen Sensor line, it is built to deliver the fit, form, and function expected from an OE-style replacement. The heated design supports sensor operation after startup, while the threaded mount and harness length help match the original installation layout.

NTK draws on its role as a major OE oxygen sensor supplier and tests these sensors during manufacturing to meet or exceed OE specifications. For buyers searching for a 1996-1997 Mercury Villager oxygen sensor or a 1996-1997 Nissan Quest downstream oxygen sensor, part number 22521 provides a specific-fit replacement option.

What It Is Used For

• Replacing a worn or slow-responding downstream oxygen sensor.
• Restoring exhaust feedback for engine management.
• Addressing sensor fault codes related to oxygen sensor performance.
• Correcting drivability issues tied to inaccurate air-fuel readings.

Installation Notes and Tips

Verify the downstream location, connector style, thread diameter, and harness length before installation. Use the vehicle's original routing path to avoid strain on the wiring, and confirm the sensor is specified for the exact application before replacement. Part number 22521 should be matched to the listed fitment only.

Quality Assurance

NTK manufactures oxygen sensors with OE-level application coverage and tests them during production to help ensure reliability and specification compliance. Part number 22521 is backed by NTK's manufacturing focus on original equipment oxygen sensor technology.