Product Information

An oxygen sensor continually detects the oxygen content in the exhaust gases of an engine. The oxygen sensor output signal informs the vehicle’s 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.

NGK manufacture two different types of oxygen sensors:

• Zirconia oxygen sensors produce a voltage which varies based on the amount of oxygen in the exhaust gas.
• Titania oxygen sensors vary in resistance based on the amount of oxygen in the exhaust gas.

Both Zirconia and Titania oxygen sensor types are produced with different numbers of wires to satisfy different needs, although it is critical to note that due to their different properties Zirconia and Titania sensors should not be interchanged under any circumstance.

Single Wire - One wire carries the sensor signal while ground return is achieved through the vehicle body. Also referred to as an EGO Sensor (Exhaust Gas Oxygen Sensor).

Two Wires - One wire is the sensor signal and the other is the sensor signal ground. Also referred to as an ISO-EGO Sensor (Isolated Exhaust Gas Oxygen Sensor). The signal ground wire in the NTK two wire (and four wire) oxygen sensor is completely isolated from the vehicle ground.

Both sensor signal wires are directly connected to one of the platinum electrodes on the ceramic element. The sensor output is immune to ground loop voltages and also to large resistances in the vehicle ground return, caused by corroded connections. No NTK two wire sensor is case grounded. Case grounded sensors have the ground wire physically attached to the sensor body. It is not recommended to replace isolated ground sensors with case ground types.

Three Wires - One wire carries the signal and two wires are used to supply a voltage to the internal heater. Signal ground return is achieved through the vehicle body. Also referred to as a HEGO Sensor (Heated Exhaust Gas Oxygen Sensor).

Four Wires - One wire is the sensor signal, one is the isolated sensor signal ground and the remaining two are used to supply a voltage to the internal heater. Also referred to as an ISO - HEGO Sensor (Isolated Heated Exhaust Gas Oxygen Sensor).

The sensor signal wire is directly connected to one of the platinum electrodes on the ceramic element. The sensor output is immune to ground loop voltages and also to large resistances in the vehicle ground return, caused by corroded connections. No NTK four wire sensor is case grounded. Case grounded sensors have the ground wire physically attached to the sensor body. It is not recommended to replace isolated ground sensors with case ground types.

The first sequence of letters and numbers before the dash provide information about the sensor element excluding the wiring and connector. The second sequence after the dash provides information about the wiring loom length and connector type.