Service Engine Soon Light – What It Means and What to Do

One of the most important signals your car’s dashboard has is the service engine soon light, which is run by a computer that turns the light on when some part of your engine is showing signs of weakened performance or trouble ahead.

If you’ve never had the service engine soon light come on, you might not know what it means or what to do when it comes on for the first time.

In this article, we aim to provide the necessary information to understand what this light signal means and what you can do to solve the underlying issue and get the light to turn off.

What is the Purpose of a Service Engine Soon Light?

The purpose of a service engine soon light is to alert the driver that the car should be taken into an auto shop to service and fix part of the engine sooner rather than later. It looks like a light that says “Service Engine Soon” or may feature an illustration of an engine. It is usually located in the dashboard of the car above the steering wheel in most brand models.

In many brands, the service engine soon light and the check engine light is the same.

In Kia, for example, it’s a symbol of an engine with the words “Check Engine” inside. Honda and Toyota are two other brand examples that use the same symbol for both. BMW, on the other hand, may show a half-full engine for moderate issues or a fully lit red engine for more serious matters.

The goal of the light is to avoid further damage that could harm the engine or the car as a whole, and in the worst case, render the car totaled.

A service engine soon light can mean several different things, but we’ll cover more on that later.

Types of Service Engine Soon Lights

There is only one kind of service engine soon light, and it’s the light with this name. The only different “types” of this light that you’ll see might be the color of the light and whether the light is blinking or solid.

What the light means may vary, and the light usually doesn’t show any further details so it is hard to know what the issue is without taking the car to a shop to be looked at by a professional.

While some people may assume they know what kind of service engine soon light they’re seeing, the only real way to know is by opening the hood to take a closer look.

Some of the most common causes to see a service engine soon light include:

  • A loose gas cap
  • Faulty spark plugs or wires
  • Low fluids
  • Scheduled service
  • Failure of the oxygen sensors
  • Mass airflow failure
  • Faulty catalytic converter

Learn more about these different causes of the service engine light later in this article.

Can You Drive With a Service Engine Soon Light On?

In most cases, yes, you can drive safely with a service engine soon light. You should still plan on bringing your car in as soon as possible, but it’s usually not the kind of scenario where you need to pull over or into the closest auto shop.

As a general rule, you should try to bring your car in within the next 100 miles to avoid further damage to the engine since you don’t know what’s wrong with it yet.

If the service engine soon light is a solid yellow or orange, it’s usually not a super serious issue and you should be able to complete the drive you’re on before taking it in.

If the light is red or is blinking, you should take that as a sign that the issue might be more serious and you should try to find the nearest auto shop that you trust to take a look and provide more insight on the matter before you decide whether to keep driving on it or to get it fixed there.

When in doubt, your owner’s manual might be able to shed some additional light on what the colors or blinking pattern of your service engine light mean.

What the Service Engine Soon Light Means

It could be any one of these issues, however, this list is not exhaustive. It could also be something else, so while you may be tempted to put on your mechanic’s hat and try to solve the issue yourself, you should opt to bring it to an expert to ensure you’re diagnosing the right problem.

  • When it stays on – the issue is consistent but may not be urgent
  • When it turns on and off randomly – it’s an intermittent problem that isn’t constant, like faulty sensors
  • When it’s flashing or blinking – the problem is severe and needs professional help quick

Certain car brands’ service engine soon lights may have different features, such as flashing, or turning colors, or even showing half the light illuminated, like in BMWs.

What Causes the Service Engine Soon Light to Come On?

It could be any one of these issues, however, this list is not exhaustive. It could also be something else, so while you may be tempted to put on your mechanic’s hat and try to solve the issue yourself, you should opt to bring it to an expert to ensure you’re diagnosing the right problem.

  • Low Fluid or Scheduled Service – If you’re a bit behind on your scheduled oil change and service, the light is likely to come on. This is usually not something extremely urgent, but you should try to bring it in within a few days.
  • New Spark Plugs – One possibility is that you need new spark plugs. Spark plugs ignite the mixture of air and fuel that is needed in the engine. If you need new spark plugs, you may notice reduced mileage, less acceleration in your car, hard starts, and a rough idle in addition to your service engine soon light turning on.
  • Loose or Faulty Gas Cap – The first thing you should check for with a service engine soon light is a loose gas cap. It can increase emissions and reduce your mileage, and it’s an easy fix.
  • Mass Airflow Sensor Failure – This sensor tells your car how much fuel it needs, and if the sensor isn’t working, the car can have a hard time starting or accelerating from idle. You can still drive with this issue, but you should fix it as quickly as you can.
  • Oxygen Sensor Failure – If your car is producing too much oxygen in its exhaust, it’s running rich, and if it’s not producing enough, it’s running lean. When this level is off, things with your car can get bad quickly, so act fast and bring it to an auto shop.
  • Faulty Catalytic Converter – A car’s catalytic converter converts the chemicals created by ignition into less harmful chemicals for the environment. If this item is failing, your temperature gauge may come on, your car may not perform as usual, and your mileage may decrease.

How to Fix Service Engine Soon Light

If your service engine light is on, here’s what to do:

First, Check the Color and Pattern

Is the light yellow or orange? Then the issue is probably not quite as severe. Is it red? Then that may call for more urgent attention. Additionally, if the light is blinking, you should have a professional take a look as soon as you can. Noticing these properties will help you decide what to do and how to fix it.

Next, Have an Expert Diagnose the Issue

Bring your car into an auto shop so they can tell you what the issue is. You don’t necessarily have to pay them for the labor of fixing it, but you will need to pay them for taking the time to look at it and diagnose the issue. In some cases, however, if it’s a complicated fix, you should just let the experts solve it.

Most use computer systems they can connect to your car to find what’s wrong, while others will diagnose manually.

Finally, Go to an Auto Parts Shop and Make the Fix

If you feel confident that it’s an easy enough fix, you can ask the auto shop attendant what part you need to solve the problem. Then, head to your closest auto parts store and purchase the correct part so you can install it yourself and save on labor costs.

You could even bypass the step of having a professional diagnose the issue by purchasing an OBD2 scanner, which is a tool you can connect to your car for a quick diagnosis of what’s wrong. To use it, plug it into the port beneath the driver’s dashboard, turn on the car, and enter any information the machine prompts you for.

Service Engine Soon Light vs. Check Engine Light

The service engine soon light is not quite the same as the check engine light, which you may have seen at some point in your car.

The service engine soon light is usually just a reminder that your car is due for scheduled maintenance or if there is a minor issue affecting the car. They’re less likely to be catastrophic, major problems.

The check engine light, however, usually indicates a serious issue with your car that requires immediate attention and fixing.


How Many Miles Can You Drive With the Service Engine Soon Light On?

While you should aim to bring your car in for a diagnosis as soon as you can, you may be able to drive about 100 miles on it if needed.

Can You Pass Inspection With the Service Engine Soon Light On?

Mandatory vehicle inspections are important to keep cars and drivers safe. To pass an inspection, a car can’t have any indicator lights on, including a service engine soon light.

Why Do My Check Engine and My Service Engine Soon Light Come On?

There are many reasons, including a loose gas cap, faulty catalytic converter, a need for new spark plugs, oxygen sensor failure, or simply as a reminder that you’re past due for scheduled service.

Can You Diagnose a Service Engine Soon Light By Yourself?

Sometimes, auto parts stores have tools that can connect with the computer of your car to determine what the issue is. In other cases, you’ll need a professional to take an up-close look. If you’re already familiar with cars and know your way around an engine, you may be able to diagnose the problem yourself.

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Author: DJ

Dave Junior is a hands-on automotive technician with experience in performing service, diagnostics, and repairs on domestic and imported vehicles. He enjoys writing and sharing his knowledge far and wide.

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