If you own a Volkswagen or Audi, there is a good chance you will see the EPC light come on. This can be a little scary, but what does the EPC light actually mean?
The EPC light is a warning light that signifies a problem with your vehicles electronic power control (EPC) system. If the EPC light is illuminated when you start your car, this usually means there is a problem with the vehicle throttle system.
Now that you have the short answer, let’s dig a bit deeper. In this post, we will specify what the EPC light means, investigate the reasons this may come on, and direct you on what to do next.
By the end of this post, you will be armed with the know how to deal with the EPC light if it does come on. Let’s get started!
What does the EPC Light mean?
The EPC light is a warning light that related to your vehicles Electronic Power Control (EPC) system. When the EPC light appears, it simply means that there is a trouble code stored in this system.
The EPC light often comes on alongside the Engine, ABS, or ESP Light. The EPC system is monitored by the engine control unit, the brake control unit, transmission control unit, and the steering control unit.
The EPC system is Volkswagen Group’s traction control system, and therefore you will also find the EPC system in Audi, Skoda and Seat car models.
What Causes An EPC Light?
The commonest causes of an EPC light include the bad throttle body, faulty ABS sensor, cracked ABS ring, bad brake pressure sensor, or the brake pedal switch. Wiring and electrical problems can also cause the EPC light.
Here are a few of the issues that would cause the EPC light to trigger:
#1. Throttle body failure.
The throttle body dictates how much air should be allowed into the engine when the gas pedal is pressed. The EPC system uses the throttle body to restrict the ability of the engine to generate power, and if the throttle body has a problem, the EPC system cannot work correctly.
Throttle bodies today for the most part are electronic, and if the throttle body has a problem, it will turn on a check engine light and an EPC light on your dashboard.
#2. Failed Brake Pedal Switch.
The brake pedal switch or brake light switch is used to know when you press the brake pedal, so the car can activate the brake lights. The switch is also used for other systems such as the cruise control system and the EPC system.
If your brake pedal switch fails, the EPC system will not have a read on when you press the brake pedal or not, which is why it will trigger the EPC light and a code for further diagnosis.
#3. Failing ABS sensor.
The ABS Sensors, or wheel speed sensors, measure the speed of each wheel on your car. It uses this data for the ABS system, but other systems in your car including the EPC system use this data as well.
Since the wheel speed sensors are located on the wheel hubs, they are exposed to dirt, rust, and water, and this can cause the sensor to fail. It may also be a failing ABS reluctor ring that the ABS sensors measure speed off of.
#4. Failed brake pressure sensor.
If you have a Volkswagen and an EPC light, there is a strong chance that the brake pressure sensor has failed.
The brake pressure sensor works similar to a brake switch, but instead of measuring ON/OFF, it actually measures the brake pressure applied through the pedal.
Unfortunately, the brake pressure sensor on many VW vehicles is built inside the ABS control module and can be difficult to change out. You may need to replace the whole ABS control module if you have a problem with a sensor, which is not cheap.
#5. A bad steering angle sensor.
The steering angle sensor is behind the steering wheel and is used to measure which position the steering wheel is in. The EPC system will use the info from the steering angle sensor to determine which direction you turn the steering wheel and adjust the brake force accordingly.
There is also a clock spring that allows the power steering wheel to turn where the wires for the steering wheel angle sensor and the steering wheel buttons go. Clock springs can fail, and if they fail, it may appear to be a failure of the steering angle sensor.
#6. A Bad Engine Sensor.
The EPC system uses a lot of different engine sensors to work properly, and if one of those engine sensors is bad, it can cause the EPC light to be on the dashboard.
Once you see the EPC light, it is clearly important to read the trouble codes to see where the problem originates from.
The engine sensors that can cause the EPC light include the MAF sensor, the IAT sensor, the ECT sensor, or the O2 sensor. You can continue reading to see how to find out which of these is causing the EPC light.
#7. Wiring Issues.
Because of all the electrical wiring modern cars have, it is highly likely that there is a wiring issue which could be causing the EPC light. Sadly, wiring problems are hard to find unless you know exactly what you are looking for.
The most likely wiring problems are broken wires, corroded electrical contacts, or burned contacts. If you have tried everything else on this list but do not have the expertise to diagnose the wiring, you may have to seek professional help.
How to repair the EPC light?
To repair the VW EPC light, you’ll need to read the trouble codes via an OBD2 scanner. After determining what the trouble codes telling you, you’ll need to continue to troubleshoot the trouble codes. If you’re just guessing at the problem, you’ll just waste money.
Here are details about the actions to take in order to repair your EPC light:
#1. Read Trouble Codes.
If the EPC light is on in your dashboard, the first thing you should do is read the trouble codes from the engine control module and ABS control module with an OBD2 scanner.
If the EPC light is on then this means there are one or more trouble codes stored in one of the control unit. Modern car models have advanced on-board diagnostic systems, meaning if there is a light on your dashboard.
There is a fault code stored in one of your vehicle’s control modules. Instead of guessing and replacing parts and spending your money in vain, you can save time and money with the trouble codes.
The vehicle’s engine control unit, the ABS control unit, the steering control unit and transmission control unit all need to be scanned in order to determine what trouble codes may be stored.
You can either take your vehicle to a shop and have them read the trouble codes or you can read the trouble codes at home with your own OBD2 scanner.
Since the cheapest diagnostic scanners only read the engine control module, and this fault could be in other control modules as well, I would suggest getting a more advanced diagnostic scanner, or letting a workshop read the other control unit codes.
#2. Check the brake light switch.
The brake light switch is a common fault that turns on the EPC light and will often be easy to check. Have someone press the brake pedal while you check the brake lights on your vehicle. If you find not brake lights, the risk that the brake lamp switch has failed is high.
However, in many vehicles, the brake lamp switch has two different currents, so even if the brake lights work, there is a good chance the switch is faulty, so it is best to diagnose it with a scan tool.
#3. Check sensor data.
If you have a diagnostic scanner but there are no decent trouble codes to continue troubleshooting from you will need to check the sensor data. Check the values from the brake pressure sensor to see if they look realistic.
You will also need to check the data from all engine sensor, brake/engine sensors and EPC related sensors.
#4. talk to a professional.
EPC systems can be quite difficult to achieve an accurate diagnosis without appropriate knowledge and tools. Therefore, if you have done the basic things above, and still can’t find anything wrong with your vehicle, it may be time to contact a professional mechanic that has experience with this issue.
While you want to avoid taking your car to a mechanic, it can get expensive, however, you will generally save money over just guessing and replacing parts that are not the issue.
If you want to remove the EPC light from your vehicle, you should definitely go with a Volkswagen or Audi workshop that has experience with these issues. You’ll also would like to check if there are any recalls or campaigns for your model VW or Audi.
Is it safe to drive with EPC light on?
Yes, it is an issue to drive with EPC light illuminated, because you don’t know why the EPC light comes on, it is always best to resolve the EPC issue as soon as possible. When the light is illuminated, it is likely there is limited functionality in your vehicle.
As the EPC system is integrated to engine control, as well as steering and brake management, it may cause engine damage or on the opposite side could create a critical incident due to limited brake or steering input.
So if you’re driving your vehicle, the EPC light came on, drive immediately to the nearest mechanic repair garage please.
Generally speaking, EPC system fault, won’t cause damage if you drive with care, the fault condition may be worse in some cases, so it is best to have the EPC checkup done ASAP.
FAQs.
Can a misfire cause an EPC light?
Yes, a misfire can cause the EPC light to come on indirectly. If the engine misfires this will hinder the overall performance of the engine and the check engine light will likely also trigger as well. If there is an issue in the engine system this can trigger an EPC light as well.
Can the EPC Warning Light Cause a Loss of Power?
Yes, the EPC warning light controls the throttle, and that might cut power to the throttle system. Sometimes when the EPC light is triggered you just can’t rev up your engine at all.
How much does it cost to fix the EPC light?
There is no fix cost to repair the EPC light since there are so many potential issues that can trigger it. Most of the time it will cost, somewhere between $100-$400, but at times it could be much more!
Is the EPC light serious?
Yes, because of the variety of issues that can trigger the EPC Light, your EPC light may not be serious. Because of this, it’s important to diagnose what exactly caused the light to come on before you continue driving, which is very crucial!
Even though the EPC system seems relatively simple in nature, it’s an advanced system that is integrated with many different systems; because of this it can be difficult to pinpoint where the problem is.
With that said, with the above information you should be able to start a quality diagnosis of why your EPC light is on your dash without wasting your money. I certainly hope this information was helpful to you!