Ignition specialist NGK is urging motorists to have independent garages make essential vehicle checks as car use rises after Covid restrictions are eased. In particular the company says Lambda sensors may have become faulty and could require replacement.

The leading supplier of original equipment spark plugs, glow plugs and NTK engine management sensors says garages should be prepared for increased demand especially as there will be a backlog of NCT testing.

Mark Hallam, Marketing Manager, NGK Spark Plugs said,  “As more and more vehicles return to the roads following the easing of the COVID restrictions, it is vitally important that motorists ensure they are roadworthy and in the best possible condition by getting them checked at their local independent garage. When the vehicles that are due an NCTs are eventually tested, many thousands will fail on emissions which will lead to increased demand for the replacement of Lambda sensors.”

NGK is the world’s largest manufacturer of Lambda sensors and supplies a market-leading range to the aftermarket under the NTK brand name. NTK Lambda sensors are also the No.1 choice of vehicle manufacturers around the world and this experience allows it to offer exactly the right sensor for every vehicle application.

The company advises motor factors to encourage garages to always go with a bespoke OE-quality Lambda sensor and steer well clear of ‘universal sensors’. 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.  

NGK says factors should help educate garages by ensuring they fit a new NTK Lambda sensor whenever they replace a vehicle’s catalytic convertor. A worn or failed sensor can result in drastically reduced control of the fuelling system which could result in increased fuel consumption, uneven running, generally poor performance or failure of an NCT emission test.

NGK recommends that the function of the sensor is checked every 20,000 miles or annually. The emissions check as part of the current NCT test 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.

A malfunction of an associated part may directly affect the performance of a sensor. An oscilloscope and gas analyser is a much more accurate way of assessing sensor performance than relying on fault codes alone.  Garages need to look for slow response times, output range and heater function.

Contaminants from poor quality oils and fuel which remain in the exhaust gases can become deposited on the sensor element affecting its operation. Even coolant from a leaking head gasket can reach the element.