What Does Service Engine Soon Light Mean (Causes & Solution)

What Does Service Engine Soon Light Mean

Has your service engine light come on? Well, if this is the first time you have ever seen that light, you may be a little bit confused as to what it means.

In fact, because your vehicle is begging you to service your engine, you may be wondering whether you will be greeted with a rather hefty repair bill.

On this page, not only are we going to tell you what the ‘service engine soon’ light means, but we are also going to tell you how you can deal with most issues related to the light. We have a lot to cover here, so you best buckle up and enjoy the ride!

What Does Service Engine Soon Light Mean?

You may also see this light referred to as the ‘check engine’ light. Although, it is worth noting that, in some vehicles, the ‘service engine soon’ light is a little bit different from the ‘check engine’ light.

If your vehicle has the two separate, then you can think of the ‘service engine soon’ light as being for issues that are quite minor and need to be dealt with soon, but not on an urgent basis. The ‘check engine’ light is for issues that need to be dealt with immediately.  

This is a light that pretty much does what it says on the tin.

When this light comes on, it indicates that there is an issue with either your engine or your transmission.

The light is telling you that you need to check it. Although, obviously, the light can’t tell you exactly what the issue is.

However, depending on the vehicle that you have, your vehicle may keep a log of the issues on its internal systems. A mechanic will be able to look at these codes to see what the issue is.

Contrary to popular belief, a service engine light doesn’t always spell disaster. In most cases, the problem is going to be rather minor.

It could mean that you have left the cap off on your vehicle’s gas inlet. It could mean that you are low on certain fluids. It could mean that your vehicle needs an annual service. Although, of course, it can also mean that you do have serious issues.

Thankfully, most of these issues will likely be spotted long before they become a major problem. They only pop up if you constantly ignore the service engine soon light. 

Read also >> Can You Read Codes Without Check Engine Light On? (Full Guide)

8 Common Reasons For a Service Engine Soon Light

It is impossible for us to write an exhaustive list of what the ‘service engine soon’ light could mean on your vehicle.

It will be dependent on your vehicle’s model. Some vehicles will flash the light for issues that other vehicles may not.

You will be able to find more information in your vehicle’s manual. This tends to run you through the main reasons behind a service engine light.

It may even give you a few tips on how to deal with the issues.

1. Your Vehicle Fluids Are Low

In most cases, that light is going to appear if one of the following fluids is low:

  • Transmission fluid
  • Brake fluid
  • Oil

It is always worth double-checking that the fluid levels are topped up. We will talk more about this later on.

2. Your Vehicle Needs a Service

As the name of the light suggests, sometimes your vehicle just needs a quick service. 

Most vehicles have been programmed to encourage you to go in for a vehicle service after you have hit a certain mileage.

The garage will then be able to carry out some minor maintenance and replace whatever needs replacing.

It is important that you do this. A regularly serviced engine is less likely to have expensive issues that need to be dealt with.

3. There Is An Issue With Your Vehicle’s Transmission

If you have noticed grinding sounds from your vehicle’s transmission, issues with switching gears, or a clutch that just won’t engage, then there could be a problem with a vehicle’s transmission.

It is likely that the ‘service engine soon’ light will come on as soon as the vehicle recognizes that there are transmission issues. 

4. You Need To Replace Cabin or Engine Filters

Every so often, you are going to need to replace your cabin or engine filters.

Cabin filters help to prevent contaminated air from getting into the cabin of the vehicle (you really don’t want to breathe fuel fumes!), while engine filters help to protect the engine.

Over time, they will get clogged. Both will lead to your ‘service engine soon’ light coming on.

5. Loose Gas Cap

As we said before, there are some minor issues that can cause a service engine light to come on. Something as simple as a loose or poorly fitting gas cap can cause that light to flick on.

Thankfully, this is an issue that can be resolved rather easily.

6. Spark Plug Issues

Spark plugs need to be replaced every so often. Spark plugs help to ensure that your vehicle starts properly.

If your vehicle starts to detect that the spark plugs are not quite working in the way that they should, that light is going to turn on.

7. Minor Issues With Your Engine 

Just about any minor issue in your engine can trigger that warning light. Sometimes, the problem can be tough to diagnose. It may be something has worked its way loose. It could be overheating. It could be that the fuel isn’t flowing through the engine properly. The only way that you can tackle these issues is by talking to a professional. 

8. Failure Of The Catalytic Converter 

The job of a catalytic converter is to clean up the exhaust fumes coming from the vehicle. It helps to cut down on pollution.

Sometimes, the catalytic converter can fail. If the vehicle detects that fuel emissions are higher than legally allowed standards, then the light will come on.

How To Deal With a Service Engine Soon Light

So, now you know a few of the reasons why that service engine soon light may appear, how do you actually deal with the problem? Well, this is going to be dependent on what is causing the issue in the first place.

Obviously, you are not going to be able to fix every single issue on your own. The vast majority of service issues related to your engine or transmission will need the help of a professional.

We are only going to tell you how to deal with issues that you can rectify yourself here. Most issues e.g. fixing a catalytic converter will require a professional. 

1. Read Your Vehicle’s Manual 

Your first job should be to pull out your vehicle’s manual. This will list the various reasons why that service engine light may come on.

In some cases, it may even give you a bit of information on how you can troubleshoot the issue without needing to go to the garage.

Remember, all vehicle models are different. There is no sense in reading generic information on troubleshooting your vehicle. Always opt for information that tells you exactly how to work with your vehicle. 

2. Take Your Vehicle In For a Service

If your vehicle hasn’t been in for a service for a while, then it may be high time to take it in. As we mentioned before, the ‘service engine soon’ light is likely to come on once you hit a certain mileage.

Once a garage has looked the vehicle over, they can reset the light for you.

3. Head To a Garage

As we said, a light is just a light. The check engine light is going to look exactly the same, whether you are dealing with a minor issue or a major issue.

While we are going to give you a few troubleshooting tips so that you are able roughly work out what the issue is, this is absolutely no substitute for heading to an actual garage and getting a diagnosis.

A garage will be able to download the codes from your vehicle. This will tell them exactly what the issue is.

Of course, you may want to go through some of the minor troubleshooting tips below, just to see whether you can save yourself a few dollars and fix the problem yourself.

4. Check Your Fuel Cap

Sometimes, the problem really is as simple as the fuel cap being loose. If you notice the light has come on shortly after you have got gas, then check the fuel cap.

If you can’t get the fuel cap to screw back into place, then buy a replacement fuel cap.

5. Check Your Fluid Levels

Your vehicle’s manual will tell you exactly how to check and replenish the fluid levels in your vehicle.

The main causes of a ‘service engine soon’ light will be dwindling supplies of transmission fluid and engine oil. Top those up, and chances are that the light will go off.

In some vehicle models, you may also want to check the brake fluid. However, if your brake fluid is leaking, this could indicate a deeper problem, and you may want to talk to a professional instead.

After all, if your brake fluid supplies are dwindling, it could impact your braking. 

Change Your Vehicle’s Filters

Depending on your vehicle’s model, this may not be something that you are able to do yourself. A change of cabin and engine filters will probably be part of a vehicle service anyway.

Still, you may want to check to see whether your vehicle’s filters have been clogged. The manual will tell you exactly how to do this. If they are, then they shouldn’t be too expensive to replace. 

Change Your Vehicle’s Spark Plugs 

Finally, if your vehicle is having trouble starting and you are seeing the ‘service engine soon’ light, then it may be time to change those spark plugs.

Once again, this is something that you should easily be able to do yourself. It is just a case of unscrewing the old spark plugs and pushing the new ones into place.

It is a job that should take no more than a few minutes.

The Difference Between Check Engine Light vs. Service Engine Soon Light >> Check out the video below:


In most cases, the ‘service engine soon’ light isn’t necessarily telling you that there is a diaster just around the corner.

It is telling you that there is a minor issue with your engine that probably needs to be dealt with sooner rather than later.

Perhaps the easiest way to fix the problem is to talk to a mechanic. They will be able to diagnose the issue. Of course, you can do some work yourself e.g. replacing filters, spark plugs, or topping up fluid levels. 




Jeff is an automotive technician, technical writer, and Managing Editor. He has held a lifelong passion for cars, with a particular interest in cars like the Buick Reatta. Jeff has been creating written and video content about transportation, automotive, electric cars, future vehicles as well as new, used for more than 18 years. Jeff is based in Boulder, Colorado.

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