Service Engine Soon light vs. Check Engine light: Meaning, Causes, and What to do

Service Engine Soon light vs. Check Engine light:

When your car is running smoothly, you probably never give a second thought to the lights on your dashboard. But when a warning light illuminates your dash and you don’t know why, it can be disconcerting – even alarming. The two engine lights that most people are familiar with are the “service engine soon lights” and the “check engine lights”. A Check Engine light and a Service Engine Soon light are both indicators of problems with your vehicle. But what is the difference between them? Is it something serious – or just a malfunctioning sensor?

How service engine vs check engine soon light work

Your car has diagnostic tools and sensors that monitor your vehicle’s systems and components—and they alert you when something is wrong (or needs maintenance) via a series of backlit symbols that display on your car’s dash. Two such symbols are the “check engine light” and the “service engine soon light”.

We know that the space on your dash isn’t big enough for a detailed explanation, so we’re here to help you understand what those symbols mean, and when to worry about them.

Service Engine Soon light vs. Check Engine Light – what is the difference?

The Service Engine Soon light and the Check Engine light are made to mean two different things. If you see your Service Engine Soon light come on, it just means it’s time for some scheduled maintenance or a regularly scheduled service. But if your car has a Check Engine light, this means there is something wrong with the engine- and it needs to be fixed as soon as possible. If this happens, you should probably take your car in to get looked at by a mechanic. Or you check the problem yourself if you have an OBD2 scanner at home.

However, some car manufacturers use the Service Engine Soon light instead of the Check Engine light when the electronics or engine malfunction detected is minor (such as a loose fuel tank cap). Some car models may also have a single light that serves as both a Service light and a Check Engine light. 

Service Engine Soon meaning (Service Due light)

This service engine light is a reminder that your car is due for service. Some manufacturers include a mileage countdown, which will trigger the light to alert you when your car is due for service.

If this service engine soon light is yellow, it means that you need to schedule maintenance soon. Your car isn’t going to break down or anything, but it’s time to make an appointment with your mechanic. If this light is red, though, stop driving and get yourself to the nearest mechanic ASAP—a red light indicates that something is seriously wrong with your car and needs immediate attention.

Service Engine Soon light Causes

Fortunately, this light usually means nothing too serious is going on with your vehicle. It could be something minor like a loose fuel cap. In most cases though, the light just means it’s time for routine maintenance.  Another possible cause is that one of your fluids is low—oil, coolant, brake fluid, or any other—or your car is plagued with minor exhaust emissions problems.

The best way to determine why your Service Engine Soon light is on is by taking your car in for a diagnostic check-up.

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What to do if your Service Engine Light comes on.

The Service Engine Soon light lets you know that there is an issue with your car that needs to be addressed- but it is not an emergency. Checking off the items below should clear the light.

  • Start with checking your repair manual or using an OBD2 scanner to diagnose what the service engine light means (may differ from car model to car model)
  • Make sure your fuel tank cap is screwed on tight—if it isn’t, there could be a leak in your fuel system which may trigger the light.
  • Then check your oil and coolant levels to see if they’re low. If they are, it may be time for an oil change or other fluids refill.
  • If the light is still on after checking all those things off, then it could be time for a scheduled engine service—such as an oil change or filter replacement—or other routine maintenance items.

Check Engine light meaning

check engine light flashes briefly

The Check Engine is a broad warning sign that some component of your car’s engine is not functioning properly. It will usually show the outline of an engine, and it could have a message (“Check Engine” or “Check”) written inside the symbol.

The CEL (or Check Engine light ) can come on for several reasons, some more serious than others.

Minor reasons for check engine light on

The Check Engine light can be triggered by anything from a loose gas cap to a sensor that’s not working properly. Also, filling your gas tank while the engine is running can trigger the light to come on (because the fuel evaporative emissions system will sense what it thinks is a leak).

Major causes of engine light on

More often than not, though, check engine alerts indicate a more serious issue with your car, and will require urgent attention. Here’s some information about the most common reasons check engine light comes on so that you know what to do next:

1. Mass Air Flow Sensor (MAF)

The mass airflow sensor measures the air coming into the engine to ensure that the right amount mixes with fuel. If the air/fuel mixture is not right, your engine might stall or refuse to start. You will see a light on your dashboard if the mass airflow sensor fails.

2. Oxygen Sensor

Just like the mass airflow sensor, this crucial part measures how much unburned oxygen is in your automobile exhaust. If it is too little or too much, it could damage other engine parts resulting in a faulty oxygen sensor which in turn creates a check engine warning.

3. Catalytic Converter

The catalytic converter is the part of your vehicle’s exhaust system and if faulty, will cause a Check Engine light situation. Can be expensive to replace and your vehicle cannot run without it.

4. Spark Plugs

Worn out spark plugs or plug wires will also bring a ‘Check Engine” light

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What to do when the Check Engine light comes on

When your Check Engine light comes on, you may be tempted to ignore it or attempt a DIY check engine light diagnosis and repair. But this is unwise. If you let things go, you’re likely to end up with bigger problems and bigger repairs in the long run. Worse, you could cause additional damage by trying DIY diagnostics and repairs yourself. Even if your car seems to drive just fine with the Check Engine light on, you may not realize that further damage is being caused to things like the catalytic converters, for instance.

Instead, take your car to a mechanic and get it serviced as soon as the Check Engine light  (or Service Soon light) comes on. They have the proper tools and experience to locate and resolve issues quickly and efficiently—before they become bigger problems.

Can I drive with Check Engine light on?

If your Check Engine light is on, the best thing you can do is to get a check engine light diagnostic check from a mechanic and get the problem taken care of as soon as possible. These systems are designed to let you know that your vehicle has a problem—and for good reason. If you ignore these engine check lights, you could be doing major damage to your car.

Can I drive with Service Engine Soon light on?

Unlike the Check Engine light, which indicates a serious problem, the Service Engine Soon light lets you know that a minor problem exists and that you should have it checked out at your earliest convenience. When this light comes on, you can safely continue driving your vehicle until it’s convenient for you to have it serviced.

How do I get the Service Engine Soon light or the check engine to go off?

Once you’ve repaired whatever problem caused the light to come on in the first place, it’ll go away on its own. But if you reset check engine light flashing

before you’ve fixed the issue, it’ll probably just come right back on in a few days. So don’t do that!

Final Thoughts on Service Engine Soon light vs. Check Engine Light

Overall, if your light alert says, “Check Engine” then you should have your car checked right away. If the light states, “Service Engine Soon” then you’re probably okay waiting until later before bringing it to the mechanic for service.

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