Bosch 13879 Oxygen Sensor - Downstream, Downstream Right, Upstream or Upstream Right

Bosch Oxygen Sensor for Mazda and Kia

Bosch Part Number 13879 is a narrow-band heated oxygen sensor built for specific Mazda and Kia applications. It provides direct air-fuel ratio feedback to the ECU, helping maintain stable combustion control and lower emissions in the vehicles listed below.

The Bosch Engineered Oxygen Sensor line draws on Bosch OE development in oxygen sensing, including faster warm-up behavior, accurate lambda feedback, and durable construction for high heat and vibration environments. This Bosch 13879 sensor uses a threaded mount, 4-wire harness, and rectangular female connector for a direct-fit replacement on select Mazda Miata, Mazda Millenia, Mazda Protege, Mazda MX-3, and Kia Sephia applications.

Key Features

• Specific-fit narrow-band heated oxygen sensor
• 4-wire design with included wiring harness
• Rectangular female connector with pin terminals
• Threaded mounting with 18 mm thread size and 22 mm hex
• Steel finish with metal housing for underbody service conditions
• Overall length: 39.4 in; harness length: 35.7 in
• Bosch Part Number 13879 for direct replacement lookup

Fitment Details

• Fits 2001-2005 Mazda Miata, upstream.
• Fits 1995-2002 Mazda Millenia, downstream right.
• Fits 1997-2000 Mazda Millenia, upstream right.
• Fits 1996-1998 Mazda Protege, downstream.
• Fits 1996-1997 Kia Sephia, downstream.
• Fits 1996 Mazda MX-3, downstream.
• Fits 1995 Mazda Protege, downstream.

What This Sensor Helps Address

• Check engine light related to oxygen sensor signal faults
• Rich or lean fuel trim conditions caused by inaccurate exhaust feedback
• Slow closed-loop response after startup
• Emissions test failures tied to sensor performance
• Rough combustion control from a worn upstream or downstream sensor

Installation Notes

Confirm the sensor position, connector style, and thread size before installation. This Bosch 13879 uses a 4-wire, heated narrow-band design with a threaded 18 mm mount, so it should be matched to the exact upstream or downstream location shown in the fitment list. Inspect the harness routing and connector condition during replacement, and verify the exhaust bung threads are clean before tightening.

Quality Assurance

Bosch Engineered Oxygen Sensor products are backed by Bosch’s long OE development history in oxygen sensing technology. Bosch uses ceramic sensing elements, controlled heater operation, and high-temperature materials to support consistent signal output in demanding exhaust environments. This Bosch 13879 is a standard replacement part built to OE-style specifications for the listed Mazda and Kia applications.