NTK 22120 Oxygen Sensor - Upstream Rear

Direct-Fit Oxygen Sensor

NTK 22120 is a specific-fit oxygen sensor for emission control service, built for applications that require a threaded, heated sensor with a 4-wire design. It is a direct-fit replacement for import and domestic vehicles, including select Mazda Millenia applications.

• Heated oxygen sensor design for faster operating response.
• Specific-fit configuration for straightforward replacement.
• Threaded mounting type with 18 mm thread diameter.
• 19.75-inch wiring harness length for application-specific routing.
• 4-wire construction for the correct signal and heater circuit layout.

Fitment Details

Fits 2001-2002 Mazda Millenia, upstream rear. This application is listed as Bank 1 Sensor 1 oxygen sensor service. NTK 22120 is also cross-referenced to Bosch 15427 for the same application.

Product Overview

As part of NTK's Direct Fit Oxygen Sensor line, this part is engineered to match OE-style fit, form, and function without requiring a universal conversion. NTK 22120 is manufactured with ceramic technology and is extensively tested during production to meet or exceed OE specifications. For Mazda Millenia oxygen sensor replacement, this direct-fit design helps maintain the correct sensor location and electrical connection expected by the vehicle's emission system.

Common Replacement Issues

• Fault codes related to oxygen sensor performance.
• Slow sensor response from a worn heated sensor.
• Incorrect signal output from a damaged wiring harness.
• Fitment problems caused by a non-specific replacement part.

Installation Notes

Verify the connector style, thread size, and harness length before installation. Use the vehicle's original sensor location and routing path to confirm the correct application for the Mazda Millenia. Because this is a threaded sensor, proper removal and installation tools are recommended to avoid damage to the exhaust bung.

Quality Assurance

NTK states that these oxygen sensors are tested during manufacturing and built to meet or exceed OE specifications. The brand is part of the NGK family and is recognized as a major original equipment oxygen sensor supplier.