BDFHYK Oxygen Sensor Downstream O2, Compatible with Mazda 3 3 Sport 2010-2013, 2.0L 2.5L l4, 18041, L54118861A9U Replacement 1PCS

This BDFHYK downstream O2 sensor is an OE-style aftermarket replacement for verified 2010-2013 Mazda 3 and Mazda 3 Sport applications that cross-reference 18041 and L54118861A9U. Before ordering, confirm the exact model year, 2.0L or 2.5L engine, original sensor number, downstream exhaust location, connector, wiring layout, lead length, and emissions configuration. A stored OBD-II code or Check Engine Light alone does not prove that the oxygen sensor has failed.

18041 Downstream O2 Sensor Fitment for 2010-2013 Mazda 3

Engine choice matters within the same Mazda 3 generation. Match the original sensor and connector before ordering.

18041 O2 Sensor Interchange References

Replacement references include 18041 and L54118861A9U. Confirm the interchange number with the vehicle application and downstream position.

18041 Downstream Sensor Position Check

This SKU is listed for the downstream oxygen-sensor position. Do not infer a universal Bank 1 Sensor 2 or Bank 2 Sensor 2 label without vehicle-specific service information.

18041 O2 Sensor Diagnosis Before Replacement

Inspect the connector, wiring, heater circuit, related fuse, exhaust leaks, intake or fuel-control faults, misfires, and catalyst operation before replacement. P0420 or P0430 does not automatically prove a downstream oxygen sensor is defective.

18041 O2 Sensor Installation Notes

• Allow the exhaust to cool before service.
• Use an O2 sensor socket or suitable wrench.
• Compare the connector and lead length with the removed sensor.
• Inspect the bung threads and start the sensor by hand.
• Use anti-seize only when permitted by the sensor instructions.
• Tighten to the applicable vehicle service specification and route the harness safely.

18041 O2 Sensor Package Contents

• 1 × BDFHYK oxygen sensor

Important: This is an OE-style aftermarket replacement, not a factory-branded part.