Tips on Fixing AdBlue Warning Lights


Small passenger cars nowadays are using diesel fuel, unlike the past where diesel engines were reserved for heavy vehicles. Several benefits have resulted in this change, including the fact that diesel stores more potential energy than regular gasoline. Besides, diesel engines possess a higher compression rate that allows them to produce more power from the fuel than gasoline engines.

Nevertheless, these engines have a disadvantage that they produce a lot of exhaust emissions. The good news is that you can inject diesel exhaust fluid, AdBlue, into the exhaust pipe to speed up the breakdown of harmful gasses.  The diesel exhaust fluid vaporizes once it enters the catalytic converter, breaking down nitrogen oxide into harmless water and nitrogen.

How AdBlue Works and Why You Need It

The Euro 6 emission regulations that passed in 2016 pose a challenge to diesel engine manufacturers. The regulations require manufacturers to find a way to minimize nitrogen-emission as a way of environmental conservation. This requirement led to the innovation of selective catalytic reduction technology, SRC, a process that neutralizes harmful emissions by injecting a catalytic liquid to the exhaust gas.

The regulation saw many 2006 diesel-powered cars use SRC technology to inject little amounts of AdBlue on exhaust gases. Once AdBlue combines with exhaust emissions, it breaks the toxic mono-nitrogen to diesel exhaust.

Understanding the AdBlue Warning Light

Your car’s AdBlue system contains a tank with a fluid level sensor, which makes refilling the tank regularly unnecessary. On your dashboard, three lights illuminate when there’s an issue with the AdBlue system.

  • Yellow warning light– this AdBlue warning light illuminates before your tank is empty to give you time to fill it up. It goes off the moment you refill the tank with exhaust fluid.
  • Red light– this is the no restarting sign and illuminates when you fail to refill your tank with exhaust fluid. When this light is on, you won’t be able to turn on your engine after turning it off. The feature ensures that you won’t drive long distances without exhaust fluid. The light turns off the moment you refill your exhaust fluid tank.
  • Fluid level plus service engine light– these two illuminate simultaneously if your vehicle computer detects a malfunction within the system. The lights mostly signify a problem with the fluid level sensor or the delivery system. Sometimes it’s a warning that you’re using the wrong fluid. You need to use a diagnostic scan tool to decode the error and understand why the light is on. You need to decipher the warning light error immediately as using the wrong fluid could cause permanent system damage.

Topping Up AdBlue

When the yellow warning light illuminates, you need to act promptly and top up your AdBlue tank to prevent it from running dry. In some cases, your manufacturer may top up the exhaust fluid free of charge as part of routine servicing. If your car has variable servicing, then it requires extra attention in which case you need to top up before service. Waiting until your car illuminates the red warning light might cost you additional recovery charges.

Putting AdBlue in the diesel tank or vice-versa is highly unlikely since the fill points differ in size. But if the unfortunate happens, you should refrain from restarting your vehicle to prevent distributing the wrongly filled fluid in the wrong parts. AdBlue is incompatible with many substances and can lead to pipework corrosion and other components in your fuel system.

If you accidentally mix the two, call for professional assistance immediately. Fixing your car after the damage can cost you several heavily, not to forget the lack of car usage until the tank is drained of all fuel.  Besides, you need to have your car checked and repaired of any damages caused by the error.

 Things to Note Using AdBlue

AdBlue is a synthetic urea which catalyzes nitrogen oxide into nitrogen and harmless steam. You may find some manufacturers referring to as “emission additive.” However, you should never add this fluid to the engine as a fuel additive. Instead, you should add it to the car’s exhaust system to act as a catalyst. Your car consumes the exhaust fluid in proportion to the engine usage meaning how often you refill your tanks depends on how much you use your vehicle. When it comes to AdBlue usage, you need to note that;

  • It can only be used in diesel engines as it complements the DPF emission reduction technology
  • Not all diesel cars with DPF technology have an AdBlue tank. However, all vehicles with an AdBlue tank feature DPF technology.
  • DPF and AdBlue warning lights are separate and don’t depend on each other to illuminate

Wrapping Up

Now that you understand what different AdBlue warning lights mean, you have a responsibility to ensure that you always have enough in your tank. Also, be extra cautious when refueling your oil tank or topping up exhaust fluid to avoid mixing the two.


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