2000105SX Auto Oxygen Sensor Air Fuel Ratio Sensor For Mazda 3 Mazda 5 LFL7-18-8G1

The 2000105SX air-fuel ratio (A/F) sensor is the upstream regulating probe used on the Mazda LF / L3 MZR 2.0 and 2.3 petrol engines across the Mazda 3 and Mazda 5 ranges. It is a direct-fit replacement for the Mazda LFL7-18-8G1 application.

Unlike a conventional narrow-band oxygen sensor, this wideband A/F sensor measures the exact oxygen content of the exhaust gas and returns a linear signal to the ECU, so the stoichiometric air-fuel ratio can be held precisely under all driving conditions.

The integrated heater brings the planar ceramic element to operating temperature within seconds of a cold start, allowing the ECU to enter closed-loop control earlier and reducing cold-start emissions. The sensor features a stainless-steel shell, a planar zirconia ceramic element, and a laser-welded protection tube against contamination and thermal shock.

• Five wires, wideband design: two wires feed the internal heater; the remaining wires serve the pump cell and reference (Nernst) cell. The sensor outputs a linear current signal rather than a switching voltage.
• Regulating probe: fitted before the catalytic converter as the ECU's primary fuel-control input; it is not interchangeable with the post-catalyst oxygen sensor.
• Direct-fit: OE-shaped multi-pin plug and pre-terminated cable — no cutting or splicing required.
• Installation position: confirm against the original sensor position on your vehicle. Always compare connector shape, pin count, cable length and thread before ordering.
• Torque: tighten to the vehicle manufacturer's specification (typically 40–55 N·m on an M18 x 1.5 boss). Do not use silicone-based sealant anywhere near the sensor.

Cross-reference numbers are listed for identification only. Always verify physical fitment — connector shape, pin count, cable length and thread size — against your original part before installation.

Vehicle list is compiled from aftermarket catalogue cross-references and is indicative only. Please confirm by OE number and by comparing the original sensor before ordering.