For California Emission Cars, this Oxygen Sensor for 1999-2000 1.8L Mazda Miata MX-5. Bank 1: replaces Mazda BP4Y-18-861C-9U the first o2 which is located in exhaust manifold. Mounted to the front of the engine.
The oxygen sensor is a critical component of the automotive fuel injection system; it constantly measures the oxygen content in the exhaust gas and helps the ECU (Vehicle Computer) ensure optimal engine operation at an industry standard of14.7.1.
Most importantly, too much oxygen in air/fuel ratio means the engine is running lean which is less than optimal causing reduced engine performance and damaging detonation. Oppositely, if there is too little oxygen in the ratio it means the engine is running rich and wasting excessive fuel and creating excess emission. Both conditions may shorten the lifespan of a vehicle's engine and catalytic converter.
Rspeed Oxygen Sensors are the result of rigorous testing on and off track to produce Oxygen Sensors that operate consistently at OE specifications; as such they increase vehicle's engine performance, lower vehicle emissions, and improve vehicle's fuel economy. To ensure longer sensor lifecycles and vehicle safety, every R Speed sensors is produced with premium materials that protect the sensor against the harsh environment inside of the exhaust pipe, which cause premature sensor failure in common in mass produced units. In addition, all R Speed 02s are tested against the sensor's function parameters to guarantee the highest quality and stability for even the most discerning Miata owners.
Unlike troublesome universal units, ours does not require any cutting or splicing as all our Miata o2 Sensors feature original style plug and play harnesses. Additionally, we build all RSpeed o2 Sensors in the Rounded hole, frontal tube, OS5 Japanese type just like the OEM units that where factory equipped with you Mazda Miata MX-5.
“R Speed, a company still building the Better Mouse Traps.” Call us old school but our philosophy is if you build a better product, smart consumers will buy it and tell others. As with all R Speed Products, we put all our resources into the product not fancy marketing campaigns or corporate excesses. With Rspeed you always get the best value on technologically superior products guaranteed. Try one of our Oxygen Sensors today and save.
First o2 Sensor Located at exhaust manifold
Replaces Mazda P4X-18-861A-9U
Perfect part, excellent price! 
