NGK Spark Plugs is the world’s largest manufacturer of Lambda sensors under the NTK brand name and supplies a comprehensive range of Lambda sensors for the Irish aftermarket. As a leader in this field Tim Howes, Deputy General Manager – Supply Chain & Technical Service, at NGK Spark Plugs has issued some timely advice on Lambda sensor replacement and sensor selection.

Tim says that due to the hostile environment in which they work, sensors are subject to a degree of wear and tear and ageing.  It is not possible to say definitively what the service life of a Lambda sensor should be due to the very different conditions that each vehicle experiences under different drivers. For example, city driving with lots of stop start operation will have a different influence on the life expectancy of a Lambda sensor compared to steady motorway use.

NTK recommend that the function of the sensor is checked every 20,000 miles or annually.  The emissions check as part of the NCT samples the exhaust gases to monitor the efficiency of the engine, exhaust system and engine control systems.  The Lambda sensor is a vital part of this system and its function is therefore influenced by many other components. If a sensor is faulty it will generally mean NCT failure.

A malfunction of an associated part may directly affect the performance of a sensor. An oscilloscope and gas analyser provides a more accurate way of assessing sensor performance than relying on fault codes alone. Tim suggests that technicians look for slow response times, output range and heater function.

On the question of fitting a replacement ‘Universal’ or ‘Bespoke’ Lambda sensors, Tim offers some important advice. He says, “A ‘universal’ Lambda sensor is designed to cover as many applications as possible by splicing in the connector from the unit being replaced. In theory this sounds like a good idea. In practice the potential for a mismatch with the vehicle's system or subsequent premature failure is very high.” He adds, “Apart from the more obvious choices of number of wires and whether it's a zirconia or titania type there are several base sensor designs to be considered with differing characteristics including heater element performance, response time performance and even internal electrical grounding.”

Tim points out that once the correct choice has been made you need to worry about making sound electrical connections and ensuring that you marry the lead wires correctly. Sensor manufacturers' wiring colours differ so you cannot always simply join the matching colours. There are also a range of problems in attempting to solder and crimp wires.

The message form NTK is that for these reasons it is far better and easier to choose a bespoke OE quality Lambda sensor. It is also worth noting that many vehicles now use wide band sensors and for this type there is no substitute other than the correct original equipment (OE) specification item.

Lambda sensor replacement is important to the performance of a vehicle and is an area of significant business potential for a garage. NTK says their bespoke OE quality range offers the best solution in this growing area.