5 Reasons Why Volvo SCR System Fault

A Volvo SCR system fault tells a fault with the vehicle emission control system. The system comprises many parts that ensure that the emission released by the diesel vehicle is reduced drastically. 

However, just like many components in the car, these parts can experience wear and fail to function. When this happens to the SCR system, the SCR system fault comes on, alongside other signs.

What is Volvo SCR System Fault?

A Volvo SCR system fault is a warning message when there is a problem with the Selective Catalytic Reduction (SCR) system. The warning message is predominant in Volvo trucks. 

The SCR system is an important part of a Volvo truck emission system. It helps to reduce the emissions produced by the vehicle. By doing this, the car remains roadworthy by law.

When the warning message comes up, it shows that the SCR system is either working poorly or not functioning at all. Many factors, including low DEF, damaged electrical components of the SCR system, and more could cause it. 

It is important to treat this problem urgently; ignoring the warning message can derate the engine, limiting the vehicle’s speed.

How does the SCR System Work? 

The SCR system is an emission control technology that helps reduce the air pollution released by Volvo diesel trucks. It can achieve this by injecting liquid nitrogen, Diesel Exhaust Fluid (DEF), into the exhaust system. 

Once the DEF finds its way to the exhaust stream, it meets with nitrogen oxides present in the exhaust. A reaction is made due to the contact, and the amount of harmful pollutants that could be released into the environment is reduced. 

By doing this, the vehicle is not just complying with the environmental laws, but also the environment is rid of dangerous pollutants like nitrogen oxide.

The SCR system also helps improve fuel economy and engine performance. It does this by reducing engine friction and promoting better output from the engine.  

Causes of Volvo SCR System Fault

Below are some common causes of the warning message SCR system fault. 

1. Low DEF fluids

Low DEF is the most common cause of the SCR system fault warning message. It could be caused by negligence on the driver’s side to check and top up the fluid. In other cases, it could be leaks that cause the low fluid. 

When DEF is low, it comes with some signs of its own. The check engine light will be triggered alongside the warning message. Also another sign is poor fuel economy and reduced engine performance. 

2. Failing components of the SCR system 

The SCR is made of different component that helps reduce the release of harmful gases. However, these components wear out due to age and other factors. You could use a diagnostic tool to get some of the SCR-damaged components. 

Components like the Diesel Particular Filter (DPF) can trigger a warning message when damaged. The DPF is a filter also responsible for reducing harmful emissions. Failure of the driver to properly maintain the filter will cause blockage. It will eventually lead to SCR system failure if not attended to quickly.  

Other common components of the SCR system that could cause the warning message include the Diesel Oxidation Catalyst(DOC) and Exhaust Gas Temperature (EGT) sensor. 

3. Overheating 

Another cause of the  SCR system fault warning message is overheating. The temperature of the vehicle should always be monitored. Excess heat could cause the SCR system to malfunction. A leading cause of overheating is low or leaking coolants

4. DEF contamination 

Contamination of the DEF fluid will make it less effective in reducing emissions. It could be dangerous because vehicles will release harmful substances into the environment. The car will also experience reduced performance and fuel efficiency. 

5. Failing ECM

A faulty Engine Control Module (ECM) will cause a lot of error codes, and warning lets to come up. In most cases, these error codes and warning lights are false.

In addition, the SCR system may be working fine; however, a failing ECM may trigger the  SCR system fault warning message. 

How to fix Volvo SCR System Fault

Many factors could cause a SCR system fault, so a proper diagnosis should be made. Parts of the SCR system can be physically inspected to get the cause. 

Physically inspecting the parts of the SCR system could be stressful and time-consuming. Using a scan tool is easier to properly diagnose parts of the SCR system that are not functioning. 

Below are ways to fix SCR system faults. 

1. Check the DEF fluid level and top up.

To access the DEF fluid level, open the truck’s hood, and check for a blur or black reservoir close to the firewall at the driver’s wide. Check the level of the fluid against the indicated line of the reservoir. 

If the fluid is low, then top up the fluid with an approved DEF fluid from Volvo. Try to follow all the guidelines provided by the manufacturer before going ahead to check and top up the fluid. 

Also, observe for any fluid leaks if you notice that the fluid gets low faster than usual. Check under the car for signs of leaks and inspects the fluid lines and reservoir. 

2. Check and fix failing SCR system parts

Find out which part of the SCR system is faulty using a diagnostic code; once the part is found, start the fixing or replacement. 

If you lack mechanical knowledge, we advise that the vehicle be given to a professional for a proper fix. A deeper diagnosis will be made, and all problems associated with the SCR system will be solved. 

3. Change contaminated DEF fluid

If the DEF fluid is contaminated, then the fluid has to be changed immediately. In this case, the DEF tank has to be drained totally. Clean the tank with de-ionized water and flush the system with the same substance. After this, refill with new DEF fluid. 

4. Solve ECM issue 

When faced with an ECM issue, try and reset the ECM. Use a diagnostic tool to wipe the ECM memory and all error codes. Once done, if the issue continues, it might require reprogramming or replacing the module. 

Final thoughts! 

An SCR system fault shows that your vehicle may not be road worthy. The SCR system is meant to reduce emissions, and if there is a problem, the car may not pass an emissions test. Being in these conditions could get you in trouble with the authorities, depending on where you stay.

  • Edmond Davis

    I'm Edmond Davis, an automotive expert with years of experience in vehicle repair, performance, and safety. I graduated from the University of Michigan with a degree in Automotive Engineering and have worked with major companies like Ford, GM, and Chrysler. I'm a trusted source of information for anyone looking to learn more about cars or improve their driving experience.

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