Mazda Z601-18-861 Oxygen Sensor Assembly

This upstream oxygen sensor (lambda probe) is engineered as a direct-fit replacement for Mazda 3 BK chassis models (2003-2009) equipped with 1.4L, 1.6L, 2.0L, and 2.3L gasoline engines. The sensor utilizes a heated zirconia planar element to deliver rapid wideband air-fuel ratio feedback to the ECU, enabling precise closed-loop fuel control and catalyst efficiency monitoring. The assembly features a 4-wire configuration with a dedicated heater circuit for fast light-off, a 4-pin connector matching the OEM harness, and an M18 x 1.5 mounting thread. It meets OEM specifications for heater resistance, response time, and durability under cyclic thermal loads. Cross-references include Denso DOX-0331, NTK OZA668-EE18, Bosch 0258986602, and Blue Print ADG07046C.