What Does SCR System Fault Mean In a Truck? (Explained)

SCR stands for Selective Catalytic Reduction; it’s an eco-friendly system that helps to reduce the Nitrogen oxide emitting from your truck or other equipment. This system is common in those vehicles that use diesel as fuel.

Diesel consists of many chemical particles that are dangerous to our environment. Ammonia is the main source of SCR system for cleaning NOx from toxic air exhausting from the truck engine.

This SCR system gets installed behind the truck engine between the air heater and furnace economizer, and the Ammonia gets injected through the ammonia injection grid. If this system fails, it’s harmful to our enviousness and that truck.

What is the Job of SCR System On A Truck?

SCR system is the result of modern science. It can separate toxic particles from a truck or other vehicle, exhausting air when they burn Diesel. By product, nitrogen, carbon dioxide, and many other harmful breaths of the air come out through the exhaustion pipe. Cars and trucks use a lot of Diesel; the number of these harmful airs is uncountable. 

The main goal of the SCR system is to break these toxic chemical bonds into environment-friendly particles. Nitro Oxide is broken down into nitrogen and water using Ammonia and DFL. The car manufacturers want to reduce the nitro oxide emission level from trucks.

How Does an SCR System Work?

The Selective Catalytic Reduction (SCR) system’s working process is simple. Its front part gets connected to the main engine. The engine burns fuel and produces Nitrogen Oxide; this gas goes to the SCR system’s aqueous area.

Diesel Exhaust Fluid (DEF) gets mixed with the engine exhaust air and starts a chemical reaction. In this process, Nitrogen Oxide breaks into Nitrogen, Oxygen, Carbon-dioxide, and Water.

After the particle gets separated, they go through more filters to purify perfectly, and in the end, they pass out through the tail pipeline. This system allows the truck engine to stay eco-friendly; now, we can create an environment without NOx gas. This system uses Ammonia as the source for cleaning and separating harmful gas into valuable gas; this is the main reason it’s called a Selective system.

What Does SCR System Fault Mean In a Truck?

The SCR system fault means that the Selective Catalytic Reduction system is not working perfectly, and it needs repair; otherwise, it will cause a lot of damage.

The SCR system cleans toxic particles from engine exhaust air; it is an important part of a modern truck. 

As we know, it’s connected to the main engine and the tail pipeline; if this system fails to work, that means danger for both the truck and our environment.

The truck will not start if a small problem shows in the SCR system, and much nitrogen oxide will get mixed into our atmosphere. 

What Causes SCR System to Fail?

The SCR system can fail for any reason, such as if the Ammonia gets stuck in the injection grid or a problem with DEF fluid.

You can’t count the number of issues in the system, but you need to stay cautious and vigilant.

Before starting the truck, check all the sensors and the SCR system; if it starts to show fault, fix that problem before going off with the truck.

Sometimes if the temperature rises to a high degree, then the circuit or the diode may burn, which will cause the permanent failure of the system.

What is an SCR Warning Light?

SCR (selective catalytic reduction) warning light works as an indicator for maximum driving distance failure.

If the maximum driving distance is 402 kilometers or 250 miles, the indicator light turns on. And it creates sound then your SCR system’s ignition switch is on.

This warning light will flash in time of failure; otherwise, it will not light up if everything is ok.

Why is SCR important?

SCR system separates Nitrogen, Oxygen, Carbon dioxide, and water from Nitro Oxide by injecting Ammonia. In this process, the toxic air from burning Diesel gets purified, which also benefits our environment.

This system requires fewer expenses; it’s a cost-effective system. All the heavy diesel trucks consist of this SCR system. 

How Do You Test an SCR?

To test a Selective Catalytic Reduction system, you need an Ohmmeter. Then follow these processes:

Step1: connect the positive lead to the anode part, and connect the cathode side to the negative lead

Step2: Follow the resistance value shown in the ohmmeter

A high resistance value means your SCR system is ok, and if the resistance value is low, that system is broken. You need to buy a new SCR system or repair the old one.

How to solve SCR system fault On Truck?

The Selective Catalytic Reduction (SCR) system keeps your engine safe from releasing Nitrogen Oxide into the environment. This system can show many faults, such as circuit breakdown, engine derate, DEF problem, etc.

Such as, when your Truck screen shows 60 min to derate, it means you can run that truck for 60 min. After that, you need to turn off your engine. Otherwise, truck speed will decrease.

Therefore, to solve SCR system faults, you need to identify the problem first and then repair or solve the cause of these problems.

What is SCR delete?

When you want to increase the life of your diesel truck engine, you need to do a system delete. If you’re going to clean your engine and increase the workability of the SCR system, you need to delete the entire SCR system. 


What is SCR on a Mack truck?

Answer: Mack trucks are for construction purposes; these trucks can lift heavy equipment. They are fast and cost-effective. Nowadays, manufacturers tend to put SCR systems on Mack trucks; this will save more money and help reduce the level of Nitro Oxide in our atmosphere.

What is the SCR system on a Volvo truck?

Answer: Volvo is one of the leading truck manufacturers; they include an SCR system in their trucks. That helps the consumers to reduce the cost of fuel and helps to keep the truck clean from releasing toxic air into our environment.

What is the SCR system on a Kenworth?

Answer: Kenworth truck consists of an SCR system means; these trucks produce eco-friendly exhaust air. SCR system allows a truck to break harmful NOx into Nitrogen and Oxygen; these are not harmful to us. So Kenworth is also trying to participate in an excellent global cause.

What to do if Your Volvo D13 is Stuck in 5 MPH Derate?

Answer: It’s a common problem in almost every Volvo truck. If your Volvo D13 is stuck in 5 MPH Derate, you need to understand that the SCR system is facing a problem with exhausting air. First, you need to check the Derated fault code and work on that part, or you can unplug the speed sensor and see if the problem is solved.

What are the special considerations of using SCR?

Answer: Selective Catalytic Reduction (SCR) is one of the best systems that create a suitable environment for both trucks and the environment. Injecting DEF into the engine’s exhausting air breaks them into eco-friendly particles. If your truck consists of an SCR system, you need to obtain all the knowledge of SCR faults and know how to fix them.

Final Verdict 

We live in an era where industry and technology are advancing rapidly, and the SCR system is proof of your technological improvement.

You can also call this system an active emission control system; it filters the engine air by injecting DEF.

Nitro Oxide is the most dangerous element that destroys our environment. Trucks can break them into eco-friendly particles through the SCR system.  Here we have tried to provide you with all the necessary information on what SCR system fault means on a truck. I hope you can understand the working process and the fault of the SCR system.

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