From NTK:
Servicing Intervals & Life Expectancy of an Oxygen Sensor
Increasingly stricter, federally mandated emissions regulations demand that you ensure your vehicle's emissions controls are in optimal form and the oxygen sensor plays a vital role in this process. In fact, bad/poisoned oxygen sensors are the leading cause of excess harmful exhaust emissions, contributing to the greenhouse effect.*
Because of the importance, therefore, placed on the service life and role of the oxygen sensor on your vehicle's emissions controls much has been written in recent years by aftermarket manufacturers and suppliers attempting to determine the life expectancy and replacement intervals of oxygen sensors. Real world conditions, however, truly dictate an oxygen sensor's life span. Due to the hostile environment in which sensors operate and the very different circumstances and drivers each vehicle experiences it would be impossible to definitively establish what the service life of a sensor should be.
Oxygen sensors are subjected to a considerable amount of wear & tear, ageing, and extreme temperatures even under normal operating conditions. Harmful contaminants, however, that may be present in your vehicle's exhaust stream can significantly reduce the life span of an oxygen sensor. Factors that contribute to the life span of the oxygen sensor include the location of the sensor on the vehicle's exhaust system. Sensors located directly in the manifold (usually 1 & 2 wire sensors) typically have a shorter life span due to the higher temperatures under which they operate and the increased exposure to harmful exhaust particulates (unspent fuel/oil). Conversely, sensors that have a heater in the thimble element (3 & 4 wire sensors) are more quickly brought up to operating temperatures, and therefore, are thus exposed to less harmful contaminants and operate under lower exhaust temperatures as they can be located further downstream in the exhaust system.
As the world's largest manufacturer and supplier of oxygen sensors, NTK brings to the aftermarket comprehensive knowledge of current and future OEM R & D, technology, and experience. All NTK oxygen sensors are extensively tested during manufacturing to guarantee quality, reliability, and above all, always meet or exceed the original equipment specifications. NTK oxygen sensors are designed for longer service life (from 80,000 up to 150,000km) and have been recognized as a leader in the industry. It is, however, always a good idea to have oxygen sensors checked at each tune-up and/or regular service intervals. With the harsh actual conditions in your vehicle's exhaust coupled with the higher temperatures of today's hotter running engines, NTK generally recommends checking your oxygen sensor at every 60,000km and/or every tune-up for any excess ageing or premature signs of sensor poisoning and contamination. Replace faulty sensors with confidence in a product and name you can trust, NTK Oxygen Sensors.
* Study conducted by California Air Resources Board (CARB)
