Volkswagen Check Engine Light ON

In this guide, you will learn what Volkswagen Check Engine Light  (CEL) means. Common problems that trigger VW engine light to stay on. You will also find step-by-step instructions on How to read VW check engine light codes yourself using an OBD2 scanner

[toc]

Symptoms

vw check engine light on

What you may notice when your VW Check Engine Light stays on. 

  • VW Engine Running Rough 
  • Engine Misfire / Car Shaking
  • Reduction or Lack of power
  • Poor throttle response 
  • Unusual sounds from the engine
  • Smoke from the exhaust
  • VW check engine light blinking
  • Engine idles high

A ‘check engine’ light on your VW is indicating something is wrong with the performance of the engine.  

Common Causes

The Check Engine Light on your Volkswagen (Jetta, Passat, Golf, Tiguan etc) can come on for a number of reasons including defective mass air flow sensor, bad thermostat, engine temperature sensor, short in main wire harness, vacuum leak, worn spark plugs and failed ignition coils.

Let's take a look at some of the most common problems that cause VW check engine light to come on. 

Causes of VW check engine light fuel cap

Gas Cap

A loose gas cap can trigger Volkswagen engine light to turn on. Make sure you tighten the gas cap until you hear it click. If you read the codes still get a code for EVAP system leak, inspect or replace the gas cap. Sometimes the seal can crack and not seal the fuel tank properly. You can drive the vehicle and the light will reset after a few driving cycles. Or use an OBD2 Scanner to reset the codes yourself. 

Ignition Coil

Volkswagens are famous for ignition coils failing frequently in their four-cylinder 1.8 and 2.0T engines. In some cases, even a brand new ignition coil can malfunction or last less than 10,000 miles. When VW ignition coils fail the check engine light will flash on and off, the engine will shake plus you will have poor throttle response. When reading the codes with an OBD2 scanner you will get codes such as P0300, P0301, P0302.

VW check engine light on due to bad spark plug

Spark Plugs

Worn spark plugs are another common problem that triggers VW check engine light to come on. Typically you should change your VW spark plugs at 90,000 mile mark. Volkswagen owners often forget to perform this maintenance and end up with CEL coming on around 120,000 mile mark. 

vw oxygen sensor location

Oxygen Sensor

Bad O2 sensors are another common reason VW check engine light comes on. The oxygen sensors on Volkswagen vehicles often fail in the 80,000 to 100,000-mile range. Volkswagens aren't the only cars suffering from oxygen sensor issues. Audi, BMW, Mercedes-Benz, Porsche along with Toyota and Honda all struggle with making oxygen sensors that last forever. 

Coolant Temperature Sensor

Volkswagen engine coolant temperature sensor can fail triggering check engine light to come on. Replacing the temperature sensor is a simple DIY fix that many VW owners can perform at home. 

 

VW Check Engine Light Always On

If your Volkswagen check engine light is continuously ON it can be due to hundreds of possible issues. You will need to read the codes with an OBD2 scanner. The problem can be something as simple as a loose fuel tank cap, a bad spark plug but it can also be an indication of a serious engine problem.

Do not disregard your ‘Check engine’ light, even if there are no other symptoms. 

VW Check Engine Light Flashing

When your Volkswagen check engine light is flashing, means the onboard diagnostic system has detected a misfire. This is due to fuel not getting burned in the cylinder. This problem is typically caused by a bad spark plug or ignition coil. But it can also be an indication of a blown head gasket or clogged catalytic converter. 

Image

Flashing check engine light is a definitive sign of abnormal combustion. Never ignore your VW engine light or drive the car for an extended time. Especially if your Volkswagen CEL is flashing. 

Driving a Volkswagen with a flashing check engine light could have a devastating effect on your engine and catalytic converter. If engine overheats, pull over and turn off the car. Never drive your VW hard or even moderately if your ‘Check engine’ light flashes.

How to read codes & Reset VW check engine light

Below you will find instructions on how to read VW Diagnostic Trouble Codes (DTC). Once you read the code, fix the problem, you can then follow the last few steps to reset your Volkswagen check engine light.

Clearing the codes without fixing the underlying issues does not fix the problem. 

What you will need

Instructions

  1. Locate an ODB port in your VW - it is usually placed under the steering wheel.
    vw obd2 port to scan check engine light
  2. Plug in your OBD2 scan tool and let it connect to the car. Turn the car ignition on, so that your dashboard illuminates (don’t turn the engine on). 
    vw check engine light turn on igntion
  3. Scan for error codes. Store codes, or write them down. Research the codes and what could be casuing the problem in your VW. 
  4. Fix the problem.  Reconnect the scanner back and select Clear Codes to reset VW engine light. 
  5. Turn the ignition off and wait for several seconds. Turn the engine on and check to make sure the check engine light is off. 
    vw check engine light

What to do?

Check vw engine

Don’t panic and think about safety first. Find a good and safe place where you can park your VW and check a few items. 

It is a good idea to get a hold of an OBD2 scan tool. You can buy one online or from local auto parts stores. Autozone and Advance Auto Parts will read the codes for free. One way or another, read the fault codes. This will give you far deeper insight into the problem.

Usually, an error code will point you to the part that might be the problem. If you can access suspected part, check it visually and check that nothing is loose or broken. 

Without a scan tool, the situation is a bit more difficult. Pop up the hood and look at the engine, check for anything that looks out of ordinary. A loose hose might cause rough running due to the vacuum leak. Water or oil on a sensor connector might cause faulty readings.

Always research the problem or codes for your type of VW. 

Also, consult the owner manual that came with your VW. You will probably be disappointed when you see an explanation such as ‘Engine malfunction. Please visit your VW dealer’. Which of course is not helpful at all.

Should I drive my VW or not?

vw check engine warning lights symbol

If your VW is still running fine with CEL on, in general, you can continue your drive. You should adjust your driving style, be moderate and don’t push it to high revs. Pay attention on anything out of ordinary regarding how your engine works including warning lights on the dashboard. Look for smoke from exhaust, rattle or knocking from the engine bay or rising engine temperature. 

If your engine displays any of the before mentioned symptoms, you should not dive it. Although you may travel a short distance, drives longer than several miles are an absolute no-no.

Frequently Asked Questions

Why is a ‘Check engine’ light in my VW on?

Car uses a ‘Check engine’ light to warn you that something is not working properly. Problems are usually related to fuel injection and ignition system, or emission control systems. 

 

Can I drive my VW with a ‘Check engine’ light on?

A ‘check engine’ light on it own doesn’t mean that you have to stop and call the tow truck. If your car runs normally, you can drive your car. Have it checked as soon as possible, though.

So, if your VW runs rough, misfires or emits black, white or blue smoke from exhaust, you should not drive it.

 

What does a flashing ‘Check engine’ light on my VW mean?

Flashing ‘Check engine’ light indicates misfire. This is very damaging for your engine and catalytic converter. Immediately ease of the throttle, as this will likely stop the misfire. If flashing continues, pull over and turn off the engine.

 

Why is my VW check engine light on and off?

If your ‘Check engine’ light is blinking ON and OFF, this means you have a misfire. Misfiring engine will damage your catalytic converter quickly, so immediately ease of the throttle. If this does not stop misfire, pull over and turn off the engine.

 

How can I access error codes in my VW’s board computer?

Unfortunately, error codes can not be viewed through a board computer. The only way to read the stored codes is by using a scan tool. You can visit your dealer or an independent workshop, or you can buy your own scan tool.

 

Are all scan tools expensive?

If you search for scan tools, you will find various scan tools with a hefty price tag. This is usually professional equipment. As an amateur or DIY, you can go with cheaper and simpler versions. If you have a smartphone, bluetooth ODB2 readers are a best option. They are very cheap, small and easy to use.

 

How can I know what the error codes mean?

Depending on the scan tool you have, you usually get a code without any written explanation. Especially if you have a cheap scan tool. Yet, this is more than enough. Just search that code and your car on the internet or forums.

 

What does VW ‘check engine’ code p0411 mean?

Error code P0411 indicates Incorrect Flow in Secondary Air Injection System (SAI). This is an emission control system that uses an air pump to flow fresh air into the exhaust system. Usual failure points are pump, hoses or check valve. Damaged exhaust system can cause this error, as well. 

 

VW check engine light no codes?

If you have ‘Check engine’ light, but there are no stored codes, this usually means that your scan tool can only read can only read generic powertrain codes. This is usually a case with cheaper OBD2 readers. VW has additional specific codes, that can be accessed by more specialised scan tools. 

 

What could cause VW check engine light after oil change?

Oil change can not cause ‘Check engine’ light. If it came on immediately after the oil change was done, probably some sensor or connector was unintentionally unplugged during this process. 

 

Contributors
Vehicle

Feedback

💡 Help us improve this article by providing feedback. No registration is required. 

Need Help?

💭 Ask car questions in our Car Forum.

Add new comment