Volkswagen EPC Warning Light & Car Shaking (Diagnose & Fix)

‍VW EPC Light Car Shaking

Volkswagen EPC light means there’s an error with your Electronic Powertrain Control.

An EPC warning light is a critical level issue, since the EPC items in your car manage important systems such as stability control, cruise control, and other engine performance items.

When the EPC light comes on, the car will limit voltage to the throttle. This will cause the throttle to only open up partially.

This saves the engine from itself, in case the engine is doing damage to itself while the EPC light is on.

When the car’s computer cuts power to the engine it is often considered to have gone into “limp mode.”

Once the EPC light is on look at the following items to start diagnosing and fixing your problems.

Throttle Body

One of the main reasons your car could be shaking while the EPC light is on is because your throttle body is malfunctioning.

A malfunctioning throttle will cause the throttle to open only partially when you hit the gas pedal.

When a throttle doesn’t open correctly, the air allowed into the engine may not match the amount of fuel that’s being delivered.

This inconsistency between an air fuel mixture can cause your engine to misfire and cause the engine to shake. When the engine shakes, this will cause your vehicle to shake.

To fix a faulty throttle body you have two options: Clean it or replace it.

Cleaning the throttle body requires you to remove the air intake hose and spray throttle body cleaner directly into the throttle.

Use a toothbrush to work the cleaning solution around. Open and close the throttle while you clean it to make sure you get all the angles.

A shaking Volkswagen car could be caused by a faulty throttle. Therefore, cleaning it might be the best option.

On the other hand, replacing the throttle body might be your best bet. For instructions on how to replace your throttle body, check out this video.

Faulty Ignition Coil

EPC warning lights convey that there is a serious issue that needs to be checked immediately.

Another reason your EPC warning light could be displaying on your dashboard and causing your vehicle to shake is that you have a bad coil.

A bad coil will cause the EPC warning light to illuminate since the ignition system is part of the Electronic Powertrain Control system on a VW.

The job of a coil is to ignite the spark plug, which in turns, ignites the air/fuel mixture inside of a combustion chamber.

And when a coil fails to operate properly,  it can cause misfires in an engine which can cause your vehicle to shake.

When an ignition coil fails to operate and the EPC light is on, you can expect your vehicle to shake mildly.

You will notice the shaking in your car’s steering wheel and it will be mildly shaking. The only way I’m aware of to fix ignition coils is to replace them.

Ignition coils usually run around $70 dollars and most auto parts stores will have your model in stock. But there is no way to repair these coils since once they start failing, they are burned out.

When your car’s Electronic Power Control light is displaying on your Volkswagen vehicle and it’s due to an ignition coil, replace the coil and restart the engine.

Replacing an ignition coil usually includes removing the engine cover, unbolting the ignition coil, removing the ignition coil, and reversing the steps to replace the ignition coil.

Faulty Fuel Injector

A fuel injector works by opening up a valve and pushing fuel into the engine’s cylinders. In your Volkswagen engine, each cylinder of your engine has a fuel injector.

So if you have a 6 cylinder engine, you have 6 fuel injectors. Each injector squirts the necessary amount of fuel into the cylinder.

This fuel is then ignited by a spark plug. The combustion that happens as a result of the ignition of fuel is what pushes the engine’s cylinder down.

When the engine cylinder is pushed down, it rotates the crankshaft, which runs the engine.

When the fuel injector fails to inject the correct amount of fuel into the engine cylinder, it can cause issues.

The main issues it can cause are incomplete combustion and misfiring. Both of these engine failures will cause your vehicle to shake.

A fuel injector usually starts failing once it becomes clogged from carbon deposits.

To clean fuel injectors, use a fuel additive. A fuel additive will clean the fuel injector valves and make them operate like new.

If the fuel additive fails to work, consider replacing the injectors. They are relatively cheap and very easy to replace.

Gas Pedal

Your gas pedal is part of the VW throttle system. If your gas pedal has a faulty accelerator pedal sensor, this can cause your car to shake while accelerating.

This will also cause error codes and your EPC light to display.

When your accelerator pedal isn’t working correctly, this means that your throttle won’t be operating in sync with your pedal.

This gives risk to vehicle revving and idling that are beyond your control.

This can be a very dangerous situation and you want this error figured out as soon as possible.

To fix this sensor, you’re going to have to replace it.

EPC lights are usually due to errors within the throttle system and a faulty pedal sensor will cause this light to illuminate on your car dashboard.

The warning systems on your car aren’t meant to be ignored, they are meant to be addressed as soon as possible. And fixing a faulty accelerator pedal sensor reduces engine vibration.

Fixing Volkswagen EPC Light Car Shaking

The first thing you want to do when diagnosing an EPC light is to get access to a scanner tool.

When you hook a OBD-II scan tool up to a VW car, it can tap into the EPC system.

From here, the car and scan tool will tell you which item on your car is failing. Some examples of codes that display on Volkswagen cars are P2138, P2122, P2127, and P2133.

From here, you will be able to narrow down as to exactly what issue is causing engine vibration.

For example, if your engine speed sensor code is displaying, this means you’ll need to replace that sensor. An engine speed sensor code won’t cause Volkswagen vehicle shaking but it will cause your VW epc light to illuminate.

But if your vehicle is shaking and your EPC light is on, check on some of the items mentioned earlier in this article. The cause is most likely one of them.

Using A OBD II Scan Tool

Using an OBD II scan tool is really simple. First, you must purchase one. You can purchase a cheap one from Amazon.

Next, you have to find the OBD port on your vehicle. On most cars, the OBD II port lives underneath the driver’s side dashboard.

Check both the left and right side underneath the driver’s side dashboard for the OBD II port.

The OBD II port is a port where you hook the OBD II scan tool up to. Once you find the OBD II port, hook up the scan tool and follow the directions outlined on the scan tool.

For most modern OBD II scan tools, you hook it up, start the car, and the car automatically is recognized by the scan tool.

Once the car is recognized by the scan tool, a menu will appear. There will be a “live data” option and a “stored codes” option. To diagnose an EPC light, choose the stored codes option.

Stored codes will tell you which code is causing your EPC light to illuminate. For example, if your rear light is faulty, the code will display something like “REAR LIGHT INOP”.

But of course each car will have different codes for their EPC light so make sure you write yours down once you get them and start diagnosing them correctly.