Cleaner and more sustainable environments are made possible by the Selective Catalytic Reduction (SCR) technology.
As with any complex system, the SCR system is subject to malfunctions that require prompt attention.
It is the purpose of this article to explain how to diagnose and troubleshoot an SCR system fault on your truck, what you should do if the fault occurs, and what to do if you experience one. Let’s get to it.
What is SCR System Fault?
When the Selective Catalyst Reduction system of a vehicle malfunctions or fails, it is called a System Fault.
A SCR system reduces emissions by injecting diesel exhaust fluid (DEF) into the exhaust stream where it reacts with nitrogen oxides (NOx).
There is a problem that must be addressed when a System Fault occurs. Drivers are alerted to the problem by the dashboard warning.
A malfunctioning sensor, a problem with the DEF supply, or an issue with the catalyst all can contribute to the problem.
If your SCR system is faulty, your vehicle’s emissions will go up, your fuel efficiency will go down, and you might even damage your engine. There may be a reduction in power, resulting in speed and performance being limited.
Why do SCR systems fail?
There are several factors that can cause a system fault in a SCR system, including:
DEF Fluid Insufficiency:
An essential part of the SCR system is DEF (Diesel Exhaust Fluid). DEF fluid leaks may trigger SCR system faults if the level of the fluid is too low or depleted.
In either case, there is a risk of DEF leaking into the engine if the DEF tank is not refilled regularly.
DEF Fluid Contamination:
DEF fluid contamination can damage SCR systems if it contains impurities or other substances.
DEF fluids can become contaminated if they are used improperly or are of low quality.
Clogged or dirty filters:
In addition to DEF and diesel particulate filters, the SCR system contains a diesel particulate filter (DPF).
It may cause a fault in the SCR system if contaminated or clogged filters affect its performance. In order to prevent this problem, filters should be cleaned and maintained regularly.
Mechanical Issues:
It can also happen when there’s something wrong with the SCR system, such as damaged catalysts, faulty sensors, or malfunctioning injectors.
SCR can be disrupted by these issues and error codes and warnings may be displayed.
Overheating:
There is a risk of faults occurring as a result of excessive heat affecting SCR systems’ components.
SCR catalysts and temperature sensors can be damaged by high temperatures, resulting in issues.
Towing, heavy loads, excessive idling, and heavy loads can all cause overheating.
If you need specific diagnostic procedures and troubleshooting steps, check the model and year of your car.
Diesel Vehicle SCR System Fault Solution
In the event that you encounter a fault with your SCR (Selective Catalytic Reduction) system, you can take several steps.
First, ensure that there is an adequate amount of DEF (Diesel Exhaust Fluid) in the tank.
The DEF fluid level should be topped up if it’s low. If you want to avoid potential problems, make sure you use DEF fluid with the specifications specified by the vehicle manufacturer.
After checking the fluid quality, proceed to the next step. SCR system faults may be caused by contamination, so make sure it is not contaminated.
The DEF tank should be drained and the fluid replaced with fresh, uncontaminated DEF if contamination is suspected.
Make sure that all filters within the SCR system are in good working order. This includes the diesel particulate filter (DPF) and the diesel exhaust fluid filter (DEF).
Filters should be cleaned or replaced if they’re dirty or clogged. Detailed instructions on how to access and maintain the filters can be found in the vehicle’s manual or by seeking professional help.
Check for mechanical issues within the SCR system if the above steps don’t resolve the issue.
A sensor, injector, catalyst element, and others may be examined as part of this process. It may be necessary for a qualified technician to repair or replace faulty components.
If a fault code is stored in your car’s computer system, clear it after you have resolved the underlying issue. In most cases, diagnostic tools or authorized service centers can be used for this purpose.
Consult with a dealership or an authorized service center if you are not able to resolve the system fault on your own.
They have technicians with expertise in diagnosing and repairing faults in SCR systems.
To ensure your vehicle is properly serviced, you should consult your vehicle’s manual or consult a professional.
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Frequently Asked Questions
What is an SCR system?
SCR stands for Silicon Controlled Rectifier, which is a semiconductor device used in various industrial applications, including induction melting and heating equipment. It can manage high currents and voltages effectively.
How can I diagnose an SCR fault?
To diagnose an SCR fault, consider the following steps:
Check for Overheating: Ensure proper cooling and monitor temperature levels.
Inspect Connections: Look for loose or corroded connections that may cause arcing.
Evaluate Alignment: Confirm that the SCR is properly aligned in its mounting.
Test Gate Pulses: Use specialized equipment to measure gate pulse width and amplitude.
Monitor Current and Voltage Levels: Ensure they remain within the specified limits.
What are the symptoms of an SCR failure?
Common symptoms of SCR failure include:
Erratic operation of connected motors or devices.
Sudden loss of speed control or complete stoppage after a period of normal operation.
Increased frequency of faults or tripping during high power usage.
Why are inspections important for SCR systems?
Regular inspections help identify performance issues early, such as:
Mechanical integrity problems within the system.
Potential blockages in the ammonia injection grid or catalyst buildup.
Seal integrity, which can directly impact system performance.
What maintenance practices should be followed for SCR systems?
To maintain optimal performance:
Regularly check and replace worn components.
Ensure proper alignment and torque settings during installations.
Monitor cooling systems to prevent overheating.
Conduct periodic inspections to identify any blockages or mechanical issues.
