NTK is the worlds largest manufacturer of oxygen sensors. NTK Oxygen Sensors are designed to maintain optimal fuel efficiency and are supplied with a direct-fit connector similar to those used by the OEM manufacturer for easy installation.Every NTK Oxygen Sensor undergoes a complex three test process, including long life, high temperature & anti poisoning, to guarantee high quality and durability. As future emissions standards become tougher, NTK is further developing oxygen sensor technologies to help provide cleaner, more efficient engines.An oxygen sensor continually detects the oxygen content in the exhaust gases of an engine. The oxygen sensor output signal informs the vehicles ECU (Electronic Control Unit) whether the AFR (Air-Fuel Ratio) is lean or rich. Based on this, the ECU adjusts the amount of fuel injected into the engine to achieve an optimal AFR.