Troubleshoot Engine

Deciphering the Service Engine Soon Light: Meaning and Reset Guide

Service Engine oil pressure

If the service engine soon light is on, this means that your vehicle is due a routine service such as an oil change or a filter change. It can sometimes mean that there is something minor wrong with the engine that you should get checked out the next time you are near home. 

The service engine light is not the same as the check engine light. If the check engine light is flashing, then this usually means that there is something more serious wrong with your vehicle.

Why Does the service engine soon Light turn on (5 Common Reasons)

On some older vehicles, the check engine light and service engine soon light can be combined into one. The meaning and severity of the problem depends on, the color of the light and whether the light is flashing or not.

However, on most modern vehicles there will be a separate check engine light and service engine soon light.

If the service engine soon light comes on when you are driving, it’s usually nothing to worry about. You should check your vehicle manual for the exact meaning, but in most cases it means that your vehicle is due a routine service or fluid top up. Here are some common reasons why the service engine light comes on.

Reason 1. Your Car Is Due A Routine Service 

All modern cars will notify you when a service is due. This is usually indicated via the service engine soon light. This can include regular service items such as engine oil replacement, new spark plugs, fuel filter replacement and air filter replacement and cabin (pollen) filter renewal.

The latest vehicles will often specify exactly which service is due, so the service engine soon light will come on and you may see a message on the car entertainment system screen describing what needs changing.

Reason 2. Engine fluids Are Low And Need Topping Up

If one or more of your engine fluids are low, this can cause a service engine soon light. Your engine has a few different types of fluids that may need topping up from time to time. These include engine oil, coolant or windshield washer fluid.

add oil to the engine
Low engine oil can trigger an SES light

Reason 3. The Diesel Particulate Filter Needs Replacing 

If your vehicle is less than 10 years old and has a diesel engine fitted, then it more than likely has a diesel particulate filter fitted. These filters have a limited lifespan and usually need replacement or deep cleaning after 125,000 miles of driving.

A service engine soon light can indicate that the DPF is clogged and needs attention. If the diesel particulate filter is blocked you will also notice a reduction in engine power and the engine may be difficult to start when cold. Some vehicles will limit the power output of the engine to prevent damage, and this may trigger the check engine light too.

Reason 4. The Ad Blue Fluid Needs Topping Up 

Newer diesel vehicles also utilise ad blue to lower emissions. The ad blue tank needs topping up every few 1000 miles, and the service engine light may come on when the ad blue levels get low.

adblue top up

Reason 5. Your Brake pads need to be replaced

Another common service item that needs regular attention are brake pads. Most vehicles these days will have a brake pad wear sensor fitted that will set off the engine service light when the brake pads wear out.

Some vehicles also have a separate brake service icon that will light up in red when the brakes need attention.

What are the different types of service engine soon light?

If your vehicle is fitted with a service engine soon light, it’s more than likely one of two types. 

Type 1. The standard service engine soon light literally says ‘service engine soon’ and lights up red on the dashboard when a service is due.

This is commonly fitted to vehicles that require servicing at fixed intervals as deemed by the manufacturer.

For example, the engine oil, air filter and cabin filter may need to be changed together once a year, the light may also come on for spark plug replacement every three years. The light will only come on as a service reminder and is not tied to the current condition of the engine or the recent driving conditions.

Type 2. A more sophisticated service engine soon light based on condition based servicing.

This service routine splits all of the major service items up into separate events, each with its own service interval. For example, service engine soon on BMWs is set up in this way.

There are a collection of engine service icons that illuminate orange or red depending on how urgent the service is. On engine startup, the icon for the next service that is due, will flash up on the display. If it is not due immediately it will flash on in orange for a few seconds, and it will display red if it is due now or is over due.

What Next: What Should you do when service engine soon light comes on?

In most cases, the service engine soon light is not an urgent warning that there is something wrong with your car. If you are driving when it comes on, don’t panic.

Here are a few steps to take when the service engine soon light comes on.

1. Check the vehicle handbook

If the service engine soon light comes on, the first thing you should do is take a look at the vehicle handbook to see what is going on. Dashboard warning lights can differ slightly from vehicle to vehicle, so it’s a good idea to reference the handbook if you are going to solve the problem by yourself.

2. Check the Service log book

If you’ve just bought the vehicle recently and it’s not brand new, then it may in fact be due a routine service. Take a look at the service book (usually stored with the vehicle manual in the glove box) and check to see when the last engine service was carried out and compare this to the manufacturer recommended service interval.

How can a Bad Starter Cause the Service Engine Soon Light to Illuminate?

When recognizing bad starter symptoms, it’s important to understand that a faulty starter can cause the service engine soon light to illuminate. A bad starter can lead to issues with the engine’s internal components, which can trigger the service engine soon light to come on. It’s essential to address starter problems promptly to avoid further damage.

3. Check Engine fluids and fluid caps

If the engine is not due a scheduled service, then the next thing you should do is take a quick look under the hood to see if anything obvious is wrong.

Start by dipping the engine oil (if your engine has a dipstick). Most cars will have a separate oil level warning light, but it doesn’t do any harm to make sure there is an adequate amount of oil in the engine.

You should also check the other fluid levels. Check the coolant level by looking at the amount of fluid in the coolant top-up bottle. It’s important to do this when the engine has cooled, as the coolant level will rise when the engine is hot. Also, don’t remove the coolant bottle cap if the engine is hot!

Locate the brake fluid reservoir and ensure that the brake fluid level is ok. Check the location of the reservoir in the handbook, but it can usually be located up under the windshield beside the master cylinder.

Brake fluid topping up

It’s also worth topping up the windshield washer fluid. Most cars have a separate warning light for the windshield fluid level, but it won’t do any harm to top it up so as to rule it out.

It’s also worth checking the transmission fluid level if possible. Many vehicles still have a transmission fluid dipstick for checking the levels. Low transmission fluid can cause all sorts of problems, and can trigger a dashboard warning light if it drops below the minimum level.

What Could Trigger the Service Engine Soon Light and the Reduced Engine Power Light in a Car?

The causes of reduced engine power can trigger the service engine soon light and the reduced engine power light in a car. Issues like a faulty throttle body, dirty air filters, or a malfunctioning fuel system can lead to a decrease in engine power and cause these warning lights to illuminate.

Should I Use OBD2 Codes to Troubleshoot the Service Engine Soon Light?

If you are wondering whether to use OBD2 codes for troubleshooting car trouble codes, the answer is yes. OBD2 codes are essential for diagnosing the Service Engine Soon light. By utilizing these codes, you can pinpoint the specific issues with your vehicle and take the necessary steps to address them.

4. Run an engine diagnostic

If your vehicle does not have a separate check engine and service engine soon light, then the light may come on if there is a bigger problem with your vehicles’ engine.

A diagnostic code reader will give you access to the engine control unit and any error codes that may be stored in memory. 

There are hundreds of different possible error codes, each relating to a particular engine system or engine component. Take a note of any error codes that are retrieved, and then clear them from memory. 

Now take your vehicle for a drive and if the service engine soon light comes back on, run another diagnostic to see if the same error codes appear. If the light doesn’t come back on, or doesn’t come back on at all it may point to a false positive, or an intermittent fault.

How to Turn Off The service engine soon Light?

The best way to reset the service engine soon light is by using an OBD 2 diagnostic code reader. A good code reader will allow you to reset a service schedule item such as an oil change interval or engine filter service interval. Doing this will usually turn off the service engine light.

Sometimes topping up a fluid, or tightening a fluid cap such as the gas cap followed by a short drive, can turn off a service engine soon light. Once the engine has recognised that the problem is now solved; then it may turn off the light itself. 

diagnostic reader

A diagnostic code reader can be used to turn off a service engine now light


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About the author

The Motor Guy

The Motor Guy is a passionate car enthusiast with a love for troubleshooting and diagnosing all sorts of vehicle problems.

With years of experience in OBD diagnostics, he has become an expert in identifying and solving complex automotive issues.

Through, he shares his knowledge and expertise with others, providing valuable insights and tips on how to keep your vehicle running smoothly.

- 12 years experience in the automotive industry
- ASE Master Automobile Technician
- A Series: Automobile and Light Truck Certification, A9 Light Vehicle Diesel Engine Certification
- Bachelor's Degree in Information Systems


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  • If my vehicle is older and doesn’t have a separate service engine soon light, just a combined check engine light, how can I differentiate if it’s indicating a routine service or a more serious issue without a diagnostic tool?

  • I’ve just noticed the service engine soon light come on in my car, and considering I’m not very versed in car maintenance, I’m worried about the potential cost and implications. How can I distinguish if the issue is minor and just needs a quick service, or if it’s something more severe that requires immediate attention?