Service Engine Soon – What Does It Mean And How To Fix It?

Imagine you’re thinking of going for a drive one day, and your fingers are just itching to turn on the ignition. But just as the engine roars into life, you notice a sudden glimmer come into view from your instrument cluster. You take a closer glance, and you notice it says, Service Engine Soon. At first, you might think to yourself, “Oh no, is something wrong with my car?”

The Service Engine Soon light has often been mistaken for the check engine light. The check engine light often means that something serious is wrong with your car. Meanwhile, the Service Engine Soon light usually means that your car’s regular maintenance schedule is due. Understanding the difference, you might think that the Service Engine Soon light on your dash doesn’t necessitate anxieties.

Indeed, you shouldn’t need to worry as much, as it’s just the car’s way of gently reminding you to take it to the workshop for a check-up. However, it’s the small things that often lead up to big repairs. So, read along with our guide here to know more about the Service Engine Soon light, what it means, and what you can do about it.

• What Is The Service Engine Soon Light?
• Service Engine Soon vs Check Engine
• Common Causes Why It Appears
• Could You Drive Safely With It On?
• Diagnosis & Troubleshooting
• Repairs & Fixes To Consider
• Final Conclusion
• Frequently Asked Questions (FAQs)

“Uh-oh. The dreaded “Service engine soon” ????” by Sharon Hahn Darlin is licensed under CC BY 2.0 .

Service Engine Soon Light

So, you might have noticed that the Service Engine Soon light is glaring at you. Now, it’s time to understand what’s going on, and what it means. Besides, this light can even come along despite there not being any clear symptoms, or signs of problems. No odd sensations, vibrations, noises, smells, or leaks coming from the car. Alternatively, the more attentive among you might just have a sixth sense that the car is a tiny bit off.

But it’s enough to make you wonder if anything is wrong at all. First, we must understand what’s prompting the Service Engine Soon light to come on in the first place. Pretty much every engine in modern cars has an electronic computer brain. They are called the engine control unit (ECU), or the engine control module (ECM).

They comprise a small computer that sits within your car’s engine bay. It’s enclosed, like a plane’s black box. The ECU is then connected to many different sensors, all placed throughout the car and its key components. These sensors are able to sense and analyze the inner machinations of the car to make sure everything is in working order.

Each component has its own threshold and is designed to work best in its pre-set optimal states. The sensors are responsible for monitoring them and then instructing other parts to work alongside them in unison. For example, being able to detect coolant temperature, accelerator pedal position, the flow and composition of air, and so on.

If, for instance, some of these components are running a bit too hot, too cold, or have signs of failing, the sensors will alert the ECU. If the ECU decides that something is wrong, it will alert you, the driver. This is done through the check engine, or the Service Engine Soon light depending on the car.

Service Engine Soon vs Check Engine

Going back to the previous section, we learned that issues within the car can prompt you with a warning. However, another confusion is that carmakers can sometimes combine both the Service Engine Soon and the check engine lights. Consequently, many people mistake these two different indicators and use them interchangeably.

Any problems from within the car might prompt either light from coming on, but the key difference is in the severity of the issue. As such, we’ve highlighted the core meaning of what makes these two warning lights distinct from one another. Here are the differences, in greater depth.

Service Engine Soon Meaning

As the name suggests, the Service Engine Soon light usually warns you that your car is due for its usual maintenance. It lights up in text, showing Service Engine Soon, or ‘Service Due’. Alternatively, it could also light up when there are minor issues with the car that are not immediate or catastrophic in nature. This is the reason why you might not be able to notice that anything is wrong with your car when it lights up.

Carmakers can program the Service Engine Soon light to come on after a set number of miles, or depending on when you’ve had it serviced prior. As robust as cars can be, every single component is still subject to wear and tear. This is given how complex a car is under the skin. It has a huge number of moving parts, constantly under strain.

Oils, coolant, spark plugs, fluids, air filters, and more might need servicing or replacement. This is normal in the upkeeping process for any car throughout its lifespan. Therefore, you can be a bit more relaxed knowing that the car is simply reminding you that it’s time for a routine service. Once you’ve sent it to the workshop to have a check-up, they will reset that Service Engine Soon light.

Check Engine Light Meaning

Compared to the gentle reminder that usually comes with a Service Engine Soon light, this one is more of a loud klaxon. It often lights up in the shape of an engine, but can also appear as text. Seeing the check engine light is always a worry and for good reason. It usually indicates that something is badly wrong with your car, and it needs immediate attention.

It might mean that a part of your car is failing, or malfunctioning, and you should have it checked up ASAP. This often relates to parts of the car that are responsible for the engine, transmission, or emissions control. Sometimes, it could be a sign that a sensor is broken. As we’ve learned earlier in our understanding of what a Service Engine Soon light is, sensors are important. It ensures that parts of the car are working in their most optimal state.

The result is better efficiency and performance while keeping wear and tear at a minimum. It might not sound serious at first, but a malfunctioning sensor would allow a car to work beyond its threshold. This could possibly snowball into a more extensive problem down the line. Alternatively, the check engine light could mean that an entire component isn’t working well, altogether.

Service Engine Soon Light Blinking

We now should be able to better differentiate the Service Engine Soon, and the check engine light. Next, we should try to dig up the root of the issue and find out what’s causing it to light up. Once again, it’s worth pointing out that most carmakers would program the Service Engine Soon light simply to show that the car is ripe for its regular service.

Nonetheless, we’ve seen some carmakers combine them under a single warning light, to indicate any and every fault. This could either be very serious or nothing at all. We highly recommend that you consult your car’s owner’s manual, and understand how your carmaker has programmed the light in. Or, give a call to a dealer or mechanic to understand more.

This should let you know distinctly what might cause the Service Engine Soon, or check engine light to turn on. In order to give you a wider, and more general look into the potential cause, we’ve combined them into a single warning beacon. Now, we’ll be looking through the issues that might prompt either light to come on, in order of severity.

Service Engine Soon, Causes #1. Routine Maintenance Alert

Some things need changing or checking up on every once in a while. Every car requires a scheduled service after a set amount of time, mileage, or usage. For example, replacing an air filter, or changing the engine oil. The Service Engine Soon light was created purposely to remind you of this. It’s a reminder that you should have it checked at your nearby mechanic or dealer, as soon as you can.

Service Engine Soon, Causes #2. Loose Or Faulty Gas Cap

This is the simplest of issues that could cause your Service Engine Soon light to appear. The ECU or ECM can sense that your fuel cap is either loose or faulty. The fuel cap ensures that the fuel tank is properly sealed. It works both ways. Nothing can get into the fuel tank, ensuring that it does not contaminate the fuel. And, it also works to make sure fuel – or fumes – does not leak outside.

Service Engine Soon, Causes #3. Low Amounts Of Fluid

A car has many moving parts. To make sure that it all works smoothly, and to regulate against wear and tear, a car has copious amounts of fluids. Engine oil, coolant, brake fluid, transmission fluids, and more are among the liquids inside a car. If the levels of these fluids are low, it might prompt the Service Engine Soon light to appear. Low fluid levels could either be a sign of a leak or just overdue for a top-up.

Service Engine Soon, Causes #4. Spark Plugs In Need Of Changing

Another cause for lighting up either the Service Engine Soon or the check engine light is the state of your car’s spark plugs. Spark plugs are what ignite the mixture of compressed air and fuel within the combustion chamber. The spark creates an explosion, which then creates energy for your car to move around.

Spark plugs are often designed to last a long time, and can easily keep working without issue for 100,000 miles or more. However, they do need to change eventually to make sure the combustion process is working at its optimal state. A faulty or failing spark plug can cause a deterioration in performance, such as misfiring or poor acceleration. It can also cause increased fuel consumption, or the car not starting properly.

Service Engine Soon, Causes #5. Oxygen Sensor Failure

For internal combustion engine (ICE) powered cars, it’s important for the engine to ensure that the air-fuel mixture remains optimal. This is what guarantees the engine not only operates smoothly and with adequate performance but also efficiently. The oxygen sensor (O2 sensor) is responsible for keeping this in check.

It does this by monitoring the amount of oxygen that has been exhausted from the engine and informs the ECU or ECM. If the O2 sensor fails, the engine could either be burning the fuel with too much (lean), or too little (rich) oxygen. The end result is subpar performance, poor fuel efficiency, and increased emissions. An O2 sensor failing would prompt the check engine light to come up, normally.

Service Engine Soon, Causes #6. Mass Air Flow Sensor Failure

The Mass Air Flow sensor, or MAF sensor, works on the opposite end of the O2 sensor. It is just as important, as it informs the ECU or ECM to know how much fuel to pump into the engine, depending on the intake composition of the air. The air changes in its density depending on variables such as temperature, and pressure.

Hence, it’s very important for the MAF sensor to tell the engine how much fuel is required. If it’s working as intended, it should alert the engine as to how much fuel is required. The end result is a clean and efficient burn. If the MAF breaks, the ECU would miscalculate the amount of fuel that is injected. Not only would this cause damage to the engine, but also result in the same problems caused by a faulty O2 sensor.

Service Engine Soon, Causes #7. Catalytic Converter Failure

This is by far among the most serious causes that could light up the Service Engine Soon or check engine lights. Burning fossil fuels, such as gas or diesel, releases loads of harmful gasses into the atmosphere around you. This is made worse for the air, as particulates are released caused by the use of toxic chemicals during the refining process of fuels.

This is why most cars have catalytic converters, placed within their exhaust system. Catalytic converters work to scrub off the harmful chemicals and pollutants that are released from the engine. Catalytic converters, although designed to last a long time, can wear out over time. This is especially true if you continue to drive a car for extended periods with failing O2 and MAF sensors.

Service Engine Soon, Causes #8. Malfunctioning Ignition Coil

Ignition coils have the primary function of converting the car’s 12-volt power supply to the thousands of volts required to ignite the fuel and start the engine. When an ignition coil begins to fail, it can lead to erratic behavior like engine misfiring.

Consequently, you’ll notice a drop in power, fuel efficiency, and overall performance. This failing component will surely trigger your Service Engine Soon light. Regular check-ups can preempt this issue and keep your car running smoothly.

Service Engine Soon, Causes #9. Faulty Fuel Injector

A fuel injector plays a vital role in managing how the fuel is delivered to the engine. If it’s malfunctioning, it might either provide too much or too little fuel. This irregular supply can harm your engine’s performance, and result in decreased mileage. Moreover, a faulty injector can lead to the engine not starting at all. As such, your Service Engine Soon light will alert you to check on them.

Service Engine Soon, Causes #10. Exhaust Gas Recirculation (EGR) Valve Malfunction

The EGR system reduces the amount of nitrogen oxide that can escape into the atmosphere. It reroutes some of the exhaust gases back into the engine intake, helping to reduce combustion temperatures.

If the EGR valve malfunctions, it can cause engine performance issues such as reduced power and poor throttle response. Not to mention, it can lead to increased emissions. A malfunctioning EGR valve can trigger the Service Engine Soon light.

Service Engine Soon, Causes #11. Transmission Issues

While the primary purpose of the Service Engine Soon light is engine-related issues, it can sometimes indicate problems with the transmission. These might include slippage, difficulty in gear shifting, or abnormal delay in engagement. Any irregularities in the transmission can strain the engine, affecting its performance and health in the long run.

Service Engine Soon, Causes #12. Bad Timing Belt or Chain

The timing belt or chain ensures the internal parts of the engine, such as the valves and the pistons, move in sync. If they’re out of alignment, it can result in significant engine damage. Thankfully, the Service Engine Soon light will often light up to alert you before catastrophic failure occurs. It’s a sign you should not ignore, as the repercussions of a snapped timing belt can be expensive and time-consuming.

Service Engine Soon, Causes #13. Failing Thermostat

The thermostat in your car helps regulate the engine’s temperature. If it fails, it could cause your engine to overheat or not reach its optimal operating temperature. Either scenario can reduce engine efficiency and increase wear and tear. Therefore, a faulty thermostat can be another reason for the Service Engine Soon light to come on.

Service Engine Soon, Causes #14. Damaged or Worn Out Serpentine Belt

The serpentine belt powers multiple peripheral devices in your car like the alternator, power steering pump, air conditioning compressor, and sometimes the water pump. To find out more, check out our guide on what does a water pump do in a car. If this belt is worn out or damaged, these systems can malfunction, potentially affecting the engine’s performance. Keeping an ear out for squealing sounds or checking the belt for wear and tear can help you preempt any serious issues.

In conclusion, the Service Engine Soon light is a guardian for your car’s overall health. While it can indicate minor issues, it can also be an early warning system for more serious problems. Being vigilant and addressing these causes promptly can save you from bigger headaches down the road. Remember, it’s always a good practice to consult with a professional mechanic to get a clear understanding of any problem your car might be facing.

How Long Can You Drive With Service Engine Soon Light On

We now know that causes that could prompt either the Service Engine Soon, or check engine lights to come on. Now we come to the question of should you keep on driving with one, or either light blinking along? The answer is a bit complicated.

First, we should know that the Service Engine Soon (and the Check Engine) light may have multiple different states. If it’s simply lighting up in yellow, orange, or an amber shade, then it might not be serious. However, if it’s flashing or blinking, or changing its color to red, then it’s warning you that the car needs immediate and serious attention.

In the end, it’s a matter of understanding how your respective car manufacturer has programmed what to inform you, whenever either the Service Engine Soon or check engine light comes on. As such, we highly recommend that you consult your owner’s manual to understand more specifically. However, our general view is that you should stop driving, and have your car looked at as soon as possible.

“But can I just ignore it, and keep driving?”, you might wonder. The Service Engine Soon light, as we’ve learned already, often indicates minor problems, or serves as a reminder for routine servicing. However, we also know that small problems can quickly, and expensively lead to bigger problems if not resolved quickly, and properly.

How Long Can You Drive With Check Engine Light On

Our recommendation is that you be wary of driving your car, and probably only drive as a last resort. The same applies if you’re seeing a check engine light, as well. After all, a car is a very complex machine, and all the hundreds and thousands of moving parts need to work in unison. Just a single fault, and would put more strain, thus causing damage to other components. It would also result in the car not working properly, thus affecting performance, fuel efficiency, emissions, and so on.

For example, let’s put ourselves in the scenario of being late to work, and needing to get there fast. You start up your car and notice an amber light that says Service Engine Soon. In this scenario, it should be okay for you to keep driving gently, and send it off for a check-up on the way home later. But while driving, be attentive to any slight changes in the behavior of your car, and do take note. Still, we recommend that you have it checked right away.

In our second scenario, let’s consider the same being late to work example again. But this time, you notice a flashing Service Engine Soon light, or it lights up in red. In this case, we highly recommend that you don’t drive. Any further use of the car, while the ECU is detecting some fault, would eventually lead to more damage, or wear and tear down the line. What could be a simple issue, might result in bigger bills later on.

How To Reset Service Engine Soon Light

You might wonder to yourself then, that there are many potential problems, both big and small, which could light up the Service Engine Soon warning. I’m sure you ought to be curious about how you could try to narrow down the problem a bit further. If anything, narrowing down the cause might just be a good way for you to plan out on how much you need to withdraw from the ATM to have your car fixed.

Your car’s owner manual should have an explanation, and hopefully an easy-to-read list. This would show all the problems that could arise if the Service Engine Soon or check engine light were to come on. Alternatively, most modern cars have onboard diagnostics. You can then use an OBD scanner that is compatible with your car. If your car is younger than 15 years old, then it might be compatible with the newer OBD2 standard. You can find these rather cheaply, often much less than $100.

There are even Bluetooth-enabled OBD scanners, allowing you to monitor them from your phone (also, check out our guide on how do I connect my phone to my car). Plug it into your car to read precisely what error codes are being thrown up by the ECU. This could easily pinpoint more precisely as to what’s causing the Service Engine Soon light to come on. It could also make for an easier way for you to understand more about what needs to be done, so you can find the right technicians to fix it.

Reset Service Engine Soon Light

But let’s say you don’t want to send it over to a workshop or dealership to have it fixed. Besides, labor costs are quite hefty given what needs to be done, especially if the Service Engine Soon light is showing only minor problems. If you have the time, there are some things that you can do very easily and quickly to fix the problems at home.

Plus, these repairs and solutions noted down below might help to make that light disappear. Or, at least fix the underlying cause of why the service engine soon light is appearing. Then, you can use an OBDII diagnostics tool to reset the service engine soon light, validating that you’ve resolved whatever’s wrong with your car originally.

1. Loose Fuel Cap

This is by far the cheapest cause for the Service Engine Soon Light to come on. Simply turn off the engine, remove the fuel cap, and tighten it back up again. Maybe you just forgot to have it screwed around the whole way through the last time you filled up your car.

Now, start the engine, and see if the Service Engine Soon light goes away. Note, that it might not immediately disappear and would require you to drive around for a bit before it does. If the light still doesn’t disappear, then the ECU may have detected that the fuel cap needs to be replaced. You can quickly buy a replacement for between $10-$20.

2. Low Fluid Levels

You can very easily check and fix this one too, while you’re at home. Turn the engine off, and check the engine bay to find all the tanks and reservoirs as needed. You can consult the owner’s manual for some help to find them. Then, check the engine oil, brake fluid, coolant, transmission fluid, and even the windscreen washers to make sure.

Every reservoir should have a marker to show the minimum level of fluid needed. If it’s too low, then you can consult your owner’s manual again to see which brand of fluid is recommended. Have it topped up, and see if the Service Engine Soon light goes away. Although, low fluid levels could also be a sign of more extensive problems, such as leaking, or needing to completely change and flush some of the fluids.

3. Professional Solutions

You might be reading that, and thinking maybe, just maybe, it’s a bit too serious for you. Or maybe you just aren’t sure about your way around a car or aren’t confident enough to fix it yourself. No worries, as there’s a wealth of different options out there, with experienced and caring technicians to do the work for you. If you’re in the US, you can use sites such as OpenBay, or YourMechanic to find quotes from nearby garages.

They are, naturally, a bit more of an expensive option given the addition of labor. But, the added expense might just be worth it to make sure your car runs smoothly and trouble-free for a few more years. The best source we have to know how much these parts will cost is using CarMD. You can look through their most recent report here, to find out the average causes and fixes for problems pertaining to the Service Engine Soon light.

The most common fault on average is a failing O2 sensor. These can cost an average of around $250, including the cost of labor. Spark plugs averaged around $170, although it’s worth noting that this depends on how many your car needs.

One spark plug per cylinder, and you can readily find them online for under $10 each. A MAF sensor would cost you a hefty $345, while a new catalytic converter is an eye-watering $900 (even with some references to our catalytic converter price lookup guide for a Honda Pilot catalytic converter – make sure you also know where to find catalytic converters for sale)!

Check Engine Light: Facts You Need to Know

1. When the “Check Engine” or “Service Engine Soon” light comes on, it indicates a potential repair or replacement of your engine or transmission.
2. Ignoring these warning signs can result in serious problems, such as complete shutdown and high expenses, including towing and emergency roadside assistance.
3. Initially, the light will show a solid color, which means your car is due for an assessment. If ignored, the light will begin flashing, which is more serious and requires an immediate visit to a mechanic.
4. Mechanics will perform a road test to determine any issues with your vehicle’s ability to drive, and then scan the codes stored in the vehicle to provide a specific diagnosis and estimate of repairs.
5. The most common reasons for the “Check Engine” light to come on include issues with the oxygen sensor, mass airflow sensor, catalytic converter, vacuum leak, or issues with spark plugs, ignition coils, or faulty gas caps.
6. It is important to have these issues checked immediately upon suspecting there may be an issue with your car.
7. The initial indicator is a reminder, which means scheduling an appointment at your earliest convenience.
8. Always check your vehicle’s lights for signs and never dismiss them, even briefly.
9. Ignoring these signs can lead to more extensive and expensive repairs down the line.
10. If you need to check engine light diagnostics, bring your vehicle into an auto repair shop as soon as possible.

In Conclusion…

In conclusion, we hope that you’ve learned a thing or two about the Service Engine Soon light. Hopefully, you’ll be better prepared the next time, if it ever lights up on your instrument cluster. A Service Engine Soon light, in short, is like a canary in a coal mine. It chirps along if something is amiss. Pay no heed for long enough, and you may be walking into a world of hurt.

It might be something as minor as a loose fuel cap, or it might require entire sensors replaced. Expensive as it may be, sucking up the expense, for now, may as well help to avoid even ruinous repair bills later on. It’s a reminder to always keep on top of your car’s condition. It’s just like practicing your own healthcare routine, maintaining good exercise, and a healthy diet.

If you practice the same care and due diligence on your car as you do with yourself, then you might never have to see that Service Engine Soon light. Always be attentive to even the smallest of problems, or if your car is behaving oddly. Do that, and your automotive companion will never let you down.

Frequently Asked Questions (FAQs)

If you’re still curious to learn more about service engine soon lights, our FAQs here might help…

What Does Service Engine Soon Mean

Unlike a check engine light, a service engine soon light often appears as a reminder to get your car serviced, rather than alerting you that something’s wrong. Therefore, the service engine soon light, if it appears in your gauge cluster, isn’t indicative of anything immediately serious (unlike a check engine light). Often, carmakers would even program it to appear automatically after a certain mileage is reached, whenever your car needs a service, or if a component is due for a change. For example, this light would show up if your car is telling you that the spark plugs need changing soon. Or, if the fluid should be flushed and swapped out in the near future. Once you’ve had some routine service done, you could then reset the service engine soon light.

How To Turn Off Service Engine Soon Light

The service engine soon light will appear as a reminder from your car that you’ll have to commit to a routine service sometime soon. Once you’ve had that service done, like changing the oil or swapping out some old spark plugs, you can then reset the service engine. This will turn the warning light off and ensures that it would no longer appear on your gauge cluster, at least not before the next scheduled service interval. The best way to turn off a service engine light is by using an OBDII diagnostics tool. Here, you can reset the servicing items, like resetting the schedule on an oil change. This should turn the light off. However, some cars are programmed to have the service engine light turn off automatically once you complete a task like changing the fluids.

Is Service Engine Soon The Same As Check Engine

Although it’s easy to confuse them, the service engine soon light isn’t the same as the check engine light. The confusion mainly lies in the fact that many automakers combine both lights together in some instances. Sometimes, certain issues with your car would light up both lights. Otherwise, a lot of automakers don’t even include a service engine soon light, preferring to rely solely on the check engine light. In essence, a service engine soon light often serves as a reminder that your routine servicing is due. This is to let you know that the oil needs changing, spark plugs need replacing, and so on. Meanwhile, a check engine light would be used as a warning that something on your car has failed or is about to fail. Often, it relates to parts of the engine, transmission, or emissions control.

What To Do When Check Engine Light Comes On

The check engine light, although mostly a sign that something is seriously wrong with your car, can also come on for seemingly simple or trivial reasons. For example, a loose gas cap is enough to trigger the check engine light. Regardless, a check engine light shouldn’t be ignored. The severity does depend on the state of the check engine light, though. If it’s lighting up and remains constant, then it might not always indicate something serious. However, if the check engine light is flashing/blinking, then you need to have it diagnosed and fixed right away. A blinking/flashing check engine light is an indicator that a major component of your car is failing or has already failed. Thus, you should avoid driving your car, and call in a mechanic to diagnose what’s wrong.

Does Check Engine Light Come On For Oil Change

Typically, a car won’t light up the check engine light just to remind you that you need to do an oil change. A lot of cars will illuminate a service engine soon light or a maintenance light (or something similar) as a reminder that you’re due for an oil change. Automakers even program these lights to appear after a certain mileage. However, a check engine light can come on if your car finds that an oil change is desperately needed. This is the case if you’re long overdue for an oil change, for example. Or, if you’re running the wrong type of oil in your car. Alternatively, it would also light up if there are problems with the oiling system itself. For instance, if there’s a lot of oily sludge building up and clogging the oiling passageways. Or, if the oil pressure is out of spec.