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Your Guide to NOx Sensors

Keeping your exhaust emissions clean is a legal responsibility that is becoming more heavily enforced as governments work to reduce environmental footprints. NOx sensors may be a small part of your heavy vehicle, but their role in this process is crucial. Integrated within the Selective Catalyst Reduction (SCR) system, NOx sensors serve as diligent detectors of impurities, facilitating vital communication with the SCR system. In this article, we’ll look at what NOx sensors are, and the important functions they perform.

Your Guide to NOx Sensors

What is a NOx sensor?

A NOx sensor is a key part of your truck exhaust system, measuring the nitrogen oxide levels in your exhaust emissions. In most regions worldwide, strict regulations govern truck engine emissions, with NOx sensors playing a pivotal role in ensuring compliance.

Most Selective Catalyst Reduction (SCR) systems use two NOx sensors. One measures the nitrogen oxide coming out of the engine, while the other measures NOx levels leaving the SCR catalyst.

Why do you need them?

In Australia, exhaust emissions are governed by the emissions standard ADR 80/03. This is based on an International standard known as Euro I-VI. Because truck owners and operators are responsible for staying compliant with these standards, the SCR and NOx sensors are incredibly important.

NOx sensors also help to improve engine efficiency. If your truck exhaust emits too much nitrogen oxide, it indicates your engine combustion isn’t working as well as it should be, alerting you to the requirement for maintenance, which will improve overall efficiency and system life.

How do NOx sensors work?

NOx sensors are part of the SCR system, which controls the level of nitrogen oxide in your engine emissions. The SCR uses diesel exhaust fluid (DEF) infused with urea to limit the NOx in your exhaust. The sensor’s job is to identify when NOx levels are too high and send a message to the SCR, allowing it to adjust urea levels accordingly.

The diesel exhaust fluid decomposes into ammonia and carbon dioxide with normal operation. DEF levels need to be monitored carefully because too much ammonia in the assembly can be mistaken for nitrogen oxide. One of the major historical issues with NOx sensors is this inability to accurately detect what is ammonia and what is nitrogen oxide, hence the need to always invest in high-quality, trusted NOx sensors.

The importance of choosing high-quality NOX sensors

NOx sensors may be relatively small, but they play an integral part of your vehicle’s operation. A good-quality truck NOx sensor should last around 80,000km before needing replacement. In the past, truck owners have been hesitant to use aftermarket sensors, preferring the more expensive OEM parts. However, advancements in technology and better aftermarket products from manufacturers with OEM technology have changed this market.

It’s important to buy quality aftermarket NOx sensors from reputable suppliers. For every great product on the market, there are many that are of substandard quality. Common reasons for NOx sensor failure include a build-up of soot or moisture contamination during installation. NOx sensors are delicate, so the more you invest in quality products, the fewer problems you can expect to encounter.

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