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Diesel Exhaust Fluid Will Not Reset – Why And What To Do?

Since the introduction of DEF (diesel exhaust fluid), manufacturers don't need to worry about making high-powered vehicles. If you're having trouble resetting the DEF on your car, then you came to the right place. We have researched why your  DEF isn't resetting and what you should do about it.

The DEF system fault is an issue that a lot of vehicle owners face, and there are a few ways to address the problem. First, pour in more than a gallon of DEF and let your car idle for a few seconds before driving it around at a low speed until the warning sign resets.

If that doesn't work, you can try resetting the engine system by disconnecting the connector of the negative battery and waiting for twenty to thirty minutes. Finally, you can reset the system with the use of an OBD2 reader to clear the fault codes.

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In this article, we will explain further what you need to do when it comes to resetting the DEF system and just what DEF does to your vehicle. Additionally, we will talk about some commonly asked questions, like how to properly store DEF, and if it is dangerous to have around the house. Continue reading to find out more.

mans hand opening a tank for Ad Blue fluid of a blue car, Diesel Exhaust Fluid Will Not Reset - Why And What To Do?

Why Your Diesel Exhaust Fluid Is Not Resetting 

If you tried refilling the DEF tank to its required amount and the warning sign still keeps flashing, know that you're not alone. Many car owners have been through this experience. But why does this happen?

For starters, you may have overfilled or underfilled the DEF tank. You need to pour in more than a gallon each time to avoid having a system error. Always leave a third of space inside the DEF tank to avoid the same issue.

Other times, the problem could be due to having a faulty sensor. If that's the case, it's best to have it checked immediately to avoid future issues.

Sometimes the problem is due to human error. For example, pouring DEF into the wrong tank is a quick method of destroying the system.

Another example is pouring the incorrect DEF fluid into your vehicle, wrecking the system in the process as well.

During these cases, it's best to take your car to an auto shop immediately. They'll easily resolve those mistakes for you—for a cost.

But if the system error is due to overfilling or underfilling the DEF tank, you can easily reset the system as we mentioned earlier.

First, pour a gallon of DEF into the tank if you underfilled it. Then, let it idle for a couple of seconds before taking it out for a slow drive until the warning sign goes away.

Woman filling a diesel engine fluid from canister into the tank of blue car

If you overfilled the DEF tank, then try disconnecting the connector of the negative battery. You need to wait for at least half an hour to drain all the power from the engine computer before turning it back on.

Lastly, you can use an OBD2 reader. This helps clear away those faulty signals.

Check out this OBD2 reader on Amazon.

What Is Diesel Exhaust Fluid?

DEF is a solution whose two main components are water and urea. Its primary function is to reduce the harmful gas emissions of vehicles with a diesel engine.

blue DEF diesel exhaust fluid in boxes inside an auto parts store

It achieves this by breaking down those harmful gasses into nitrogen and water. Despite being around for just a little over a decade, DEF is playing a massive role in reducing air pollution. And all of this comes without having to sacrifice power and efficiency from the car's engine.

Check out this box of diesel exhaust fluid on Amazon.

What Happens To A Car Without Diesel Exhaust Fluid?

When you ignore the car's warning signs about refilling the DEF tank, your vehicle will  go into what many people call the limp mode. During this state, your car will run very slowly, as it's unable to generate enough power.

This is to make sure you don't harm the emission system and damage the engine. This safety feature protects both your car and the environment. 

How To Store Diesel Exhaust Fluid?

A white canister with a diesel exhaust fluid DEF for reduction of air pollution standing near a blue car

With proper storage, DEF has a shelf life of two years. During that time, you must keep it inside a well-sealed tank to prevent it from evaporating and attracting minerals from the air.

When choosing a tank, avoid using certain metals. Some of these include aluminum, carbon steel, zinc, and copper. That's because DEF can corrode these materials over time.

Place the tank in a cool environment, such as a garage. Keep it away from direct sunlight and open air. Make sure that the storage temperatures are between 86 degrees and 12 degrees Fahrenheit.

You do not want the DEF to evaporate or freeze due to fluctuating temperatures. Once these are all in place, storing DEF at your home is easy.

What Contaminates Diesel Exhaust Fluid?

Two of the most common contaminants when it comes to DEF are hard water and diesel fuel. In the case of the former, you can use a vinegar solution to resolve the issue.

Mix in a quarter of vinegar with three-quarters water before pouring it inside the DEF tank. Then allow the vehicle to run for half an hour before draining out the tank. From there, you can refill it with a new gallon of DEF.

If you wish to avoid hard water, using a water filter when pouring DEF will go a long way. Ignoring hard water inside the tank will lead to it crystallizing before eventually causing the pump to fail.

When it comes to diesel fuel, you need to use a petroleum-based solvent. Pour that into the tank and repeat the same steps for cleaning out hard water.

Leaving diesel inside the DEF tank can cause abrasions to the pump. This in turn will lead to rust and dirt, leading to a system failure.

How Much Does It Cost To Repair A Diesel Exhaust Fluid System?

Costs of car buying, service, repair, insurance and renting concept

If you are having trouble with your DEF system or there's an unexpected issue that you're not sure how to resolve, then you should take your car to auto shop.

The mechanic can tell you whether the DEF system needs cleaning or a complete overhaul.

Generally, it will cost you around $800 to $1,500 to replace certain parts of the DEF system and clean the filter. A complete overhaul of the system will set you back between $2,000 and $5,000 on parts. Those prices do not include labor.

At the end of the day, you are looking at a price range of between $4,000 and $10,000. So it's best to take good care of your vehicle's DEF system. Don't let even the smallest issue get past you.

Note that different car models don't share the same price tag when it comes to repairing and replacing a DEF system. You should look up how much your specific car's model will cost you before making a decision.

Is Diesel Exhaust Hazardous To Keep Around The House?

Despite the role that DEF plays in your vehicle, it's not hazardous or difficult to handle. You don't need to wear protective gear when pouring DEF into its respective tank.

As we stated earlier, it's not that difficult to store around your home, as there's no risk of it exploding. It's not combustible, flammable, or toxic.

Still, that doesn't mean you can pour a bucket of it over your head. DEF is corrosive to the skin, so you need to wash it off thoroughly with clean water and soap.

Do you want to find out more about DEF? Check out the link below:

Is Diesel Exhaust Fluid A Hazardous Material?

To Wrap Up

mans hand opening a tank for Ad Blue fluid of a blue car

If the DEF warning sign starts flashing on the dashboard of your car, there's no need to fret. Simply pour a gallon of DEF into your car and let it idle for a few seconds before driving around to make sure the warning sign goes away.

If that doesn't work, you have the option of either detaching the connector of the negative battery and leaving it for around half an hour, or using an OBD2 connector to simply reset the error code.

If you don't feel confident enough in doing any of these procedures, you can call in a professional mechanic to take a look at your car and help you out.

Did you enjoy reading this article? If so, consider checking out these posts for even more information:

Diesel Exhaust Fluid Dosing Malfunction; What Could Be Wrong?

How To Drain Diesel Exhaust Fluid