Most modern cars are controlled by the ECM (Electronic Control Module) linked to multiple vehicle sensors. These sensors control and monitor the performance of your vehicle’s myriad systems and components to optimal performance.
The ECM sends you an alert via backlit symbols like the service engine soon light on your vehicle’s dashboard whenever there is a subpar performance.
So what does this light indicate? Should you be scared? Is it something that you can handle yourself? How long can you drive when you notice this particular light?
Should you get a tune-up? All these questions are bound to arise, especially if you haven’t experienced such issues before.
This article will provide relevant answers to your questions about this particular alert from your car’s sensors. Read on to find them.
Understanding the ‘Service Engine Soon’ Light
Let’s first review what ‘service engine soon’ and ‘check engine’ lights mean. Simply put, they’re an early warning sign that something isn’t right with your car.
It’s no different from when a raised body temperature or first sniffle reveals that an illness is approaching. In the case of your vehicle, these warning lights mean that the onboard diagnostic system has detected an issue that needs attention.
These alerts are often for something simple like a loose gas cap or a disconnected hose. However, these lights can also indicate more serious issues, like engine misfires or a faulty catalytic converter.
These sophisticated warning lights are relatively new in the automotive world. More basic “idiot lights” first appeared in the 1930s, but these didn’t trigger until something serious (like high engine temperature) occurred.
There were no advance notices of problems ahead. If one of these lights went off, your car was already in trouble.
The 1970s saw the rise of car pollution control systems, followed by rudimentary technology in the early 1980s to monitor these components.
These first-generation onboard diagnostic (OBD) systems (known as OBD I) were proprietary car computers for each automaker, causing confusion among independent mechanics and DIY car owners.
This all changed in 1996 with the introduction of OBD II (or OBD2), a standardized system for vehicle diagnostics. Since then, every car sold in the U.S. has been required to have this universal way of monitoring and diagnosing problems.
These OBD II mandates require a universal interface (the port is usually under the dashboard) and standardized trouble codes (there are thousands). Professional auto technicians, amateur mechanics, and ordinary car owners all work off the same playbook.
For example, P0420, a diagnostic trouble code (DTC) for a malfunctioning catalytic converter, light means the same thing in a Ford as it does in a Honda. However, some automakers have added codes to help the diagnostic process.
OBD II continuously monitors a wide range of components and systems, such as the engine, transmission, emissions controls, and numerous sensors. If it’s electronic and related to vehicle operations, the OBD II system is likely monitoring it.
When a problem is detected, the system logs a DTC and illuminates the service engine soon or the check engine light on to warn you.
Unlike the idiot light or OBD I days, there’s less guessing about the issue. DTCs help technicians pinpoint the problem, which speeds up repairs and minimizes costs.
Significantly, the service engine soon light and the check engine light (CEL) differ from a ‘maintenance required’ or ‘service due’ light. The latter are maintenance reminders for an oil change or other standard service.
In contrast, a service engine soon light is an alert that the OBD II system has detected a problem that should be promptly addressed to prevent potential damage or safety issues.
How Is the Service Engine Soon Light Different From the Check Engine Light?
The check engine light (CEL) or malfunction indicator lamp is generally more urgent than the SES light. It turns on when your car detects more serious issues, like a leaking fuel tank or misfire. Issues that trigger the CEL typically need immediate attention.
Meanwhile, the service engine soon light usually points to routine maintenance needs, like an oil change or filter replacement. While these aren’t urgent, you still need to address them ASAP.
Wondering what to do if the service engine soon and check engine light turn on together?
You should immediately pull over, turn off the vehicle, and get the underlying issue fixed by a qualified mechanic.
NOTE: On some vehicles, the SES light is the same as the malfunction indicator lamp and signals a serious engine problem.
Next, read on to uncover what issues can illuminate a service engine soon light.
What Does the Service Engine Light Mean?
The Service Engine Soon light indicates that it’s time for regular maintenance or repair. It’s used to alert you to a problem without causing serious alarm. Whatever has gone wrong is likely not severe, but it still requires your attention.
This warning light doesn’t have a picture attached to it. Instead, the words “SERVICE ENGINE SOON” appear on the dashboard. The letters are lit up with an amber-colored light.
7 Causes of ‘Service Engine Soon’ Light
There are several reasons why your vehicle might display this symbol. Here are some of them:
#1. Vehicle Service Alert.
Your vehicle needs routine maintenance to keep it functioning optimally. It is often best to implement this maintenance after a given amount of time, mileage, or usage.
You are bound to see the service engine soon light once your vehicle is due for its routine service check.
#2. Fuel-filler Cap Issues.
Your vehicle’s ECM will be quick to detect when the fuel cap has gone bad or is simply faulty. The fuel cap serves to keep the fuel tank airtight.
When there are issues, the tank is no longer airtight; there could be a drop in mileage or increased emissions. The ECM detects these changes the indicator light is triggered.
#3. Low Oil.
Your vehicle needs engine oil for the lubrication of the engine’s components. The oil levels have to be at an optimal level for the engine to perform at its best.
When the oil level is below the optimal level the oil pressure drops. The ECM detects the drop in oil pressure, and the indicator light goes on.
#4. Spark Plug Issues.
Your vehicle’s spark plugs are another reason why the service engine soon light on your dashboard might come up. The spark plugs are responsible for igniting the air/fuel mixture within the combustion chamber.
Faulty spark plugs will cause issues like poor acceleration, misfiring, starting problems, and increased fuel consumption. In some severe cases, your car won’t start. Once any of these issues are detected by the car’s sensors, the service engine soon light is triggered.
#5. Oxygen Sensor Issues.
Your car’s oxygen sensors are responsible for keeping the air-fuel mixture at an optimal level. It keeps tabs on the amount of oxygen and relays this data to the ECM.
A problem with the oxygen sensors often leads to an imbalance in the air-fuel ratio, leading to poor engine performance, increased emissions, and high fuel consumption.
Any of these problems are enough to prompt the Infiniti service engine soon light (for example) to go on.
#6. Mass Air Flow Sensor Problems.
The mass air flow sensor monitors how much fuel should be pumped to the vehicle’s engine based on the amount of air that the engine receives.
When this sensor goes bad, it no longer relays this information to the ECM, and the car starts to experience certain problems. Some of the problems that might trigger the service engine soon light include hard starts, stalling, rough idling, and acceleration issues.
#7. Catalytic Converter Issues.
Your car is fitted with a catalytic converter that detoxifies the harmful chemicals released into the environment when the engine burns petrol or diesel.
Although this component is built to last, it can wear off after a while leading to a drop in engine performance and an increase in temperature. Any of these two issues are enough to make the service engine light indicator come on.
Now that you know the service engine soon meaning, let’s look at what you can do about it when you see it on your instrument cluster.
What Should You Do When the “Service Engine Soon” Light Comes On?
#1. Flashing/Solid/Color of the light.
Again, as mentioned above, some cars have a Service Engine Soon light and/or a Check Engine light while others have one or the other.
Whether the light is flashing or solid usually indicates what severity the issue is. Some manufacturers even go as far as color code the indicator.
Solid yellow usually represents a minor issue and you should take care of it in a reasonable amount of time.
Flashing red suggests a serious problem that may require you to pull over whenever you are able and turn off the engine immediately. Bring your car into a shop and pay them to do an inspection rather than drive it if you are unsure and want peace of mind.
#2. Pay a shop to diagnose the problem.
Of course, there is always someone who wants to take your money in regards to car repairs. This typically involves setting up a time, dropping it off, and allowing for diagnostic time frame up to half of a day.
If you don’t have the luxury of a second vehicle you will need a friend or family member to follow you to drop it off and pick it up or simply take an Uber both directions.
You could pay upwards of $100 not including the ride if you did pay for one. The good news is, you get to find out exactly why the light came on.
If you agree to let that shop repair the problem, some shops may waive the diagnostic fee. Just make sure you choose a shop you trust; it is the last thing you want to be paying too much for something small (markup on labor).
#3. Bring your car to an auto parts store.
You can also bring your car to the nearest auto parts store, though they are not going to be as thorough as a shop.
Most auto parts stores offer a free service as part of their customer service, where they will check with an OBD II scanner and tell you what it says.
This service can be much faster than going to a shop and at very worst if it is something small you may be able to fix it yourself.
Having identified what to do when a Service Engine Soon light comes on. Let’s move on to another alternative, you can purchase a OBD II scanner and diagnose it yourself.
How Do I Fix My Service Engine Soon?
There are two options to go about fixing the service engine soon issue. You could take the DIY route or get professional help.
#1. Check Gas Cap.
If you’ve pulled away from the fuel station when the Service Engine Soon comes on, you should start by checking the gas cap. Pull over wherever it is safe and pop the gas cover. If the cap isn’t on tightly enough, secure it better and see if the light turns off.
If the cap is on tightly, but you notice cracks or imperfections, you will need to get a new cap. The same is true if the cap is missing. Thankfully, you shouldn’t need to spend more than around $10 to get a cap at an auto parts store.
#2. Check And Top Up Fluid Levels.
The next step would be to take a look at all of the fluid levels. Start with the oil. Pull the dipstick and wipe it off with a clean rag.
Pull it back out again to read the levels. If it’s low, add some oil. If the oil appears to be contaminated, you should perform a complete change with a new filter.
After checking the oil, move on to the other fluids. You should examine the level and condition of both the coolant and transmission fluid. If either of these appears to be low, add some compatible fluid to the reservoir.
#3. Read Trouble Codes.
Whenever a fault is set in the ECU, codes are available to show you what’s wrong. With a compatible code scanner, you can read the DTCs to determine what’s going on. Plug your OBD-II scanner into the port located under the steering wheel.
Once you get the code, you can use our library to figure out what’s going on. We have a complete trouble code resource guide that shows you the meaning of the most common codes and outlines some possible fixes.
#4. Check Service History.
Hopefully, you are tracking the service you’ve performed on your car and when. With this information, you should be able to easily tell what’s due based on the odometer reading now.
Perform everything that the manufacturer recommends for the specified interval that you are at. While these services may not turn off the light, it’s important to keep up with the schedule to keep the vehicle in good running condition.
#5. Contact A Professional.
Not everyone should attempt to fix the Service Engine Soon light on their own. If you don’t have a lot of expertise or you lack the equipment needed for diagnostics, it may be best to visit an auto repair shop instead.
Shop around the local professionals in your area. Ask what their experience is and evaluate the labor rates. You don’t need to visit the dealership and pay the higher prices unless you prefer to do business with these shops.
When to Seek Professional Help
While some “Service Engine Soon” light issues can be resolved with simple DIY repairs, others require the expertise of a qualified mechanic. Here are some situations where professional help is recommended:
- You are not comfortable working on your car. Automotive repairs can be complex and require specialized tools and knowledge. If you are not confident in your abilities, it’s best to leave it to the professionals.
- You are unable to retrieve or interpret the DTCs. If you don’t have access to an OBD-II scanner or are unsure how to interpret the codes, a mechanic can diagnose the problem for you.
- The problem is complex or difficult to diagnose. Some issues can be difficult to pinpoint, even with the help of DTCs. A mechanic has the training and experience to diagnose complex problems.
- You are experiencing significant performance issues. If your car is running poorly, it’s important to have it checked by a mechanic as soon as possible.
- The light flashes. A flashing “Service Engine Soon” light typically indicates a more serious problem, such as a severe misfire, that could damage the catalytic converter.
Preventive Measures
Addressing the Service Engine Soon Light promptly is essential. Taking preventive measures can keep your vehicle running smoothly and avoid costly repairs. Here are some key steps you can take:
Regular Vehicle Maintenance
Regular maintenance is crucial. Follow your vehicle’s service schedule to prevent issues. Check the owner’s manual for guidance.
- Inspect belts and hoses
- Check fluid levels
- Replace air filters
Ensure tire pressure is correct. This helps with fuel efficiency and safety.
Timely Oil Changes
Changing the oil on time is vital. Clean oil lubricates engine parts. It also helps to remove dirt and sludge.
| Mileage | Oil Change Frequency |
|---|---|
| Every 3,000 miles | Conventional Oil |
| Every 5,000 to 7,500 miles | Synthetic Oil |
Monitoring Dashboard Indicators
Pay attention to your dashboard. The Service Engine Soon Light alerts you to potential issues.
- Check engine temperature gauge
- Observe fuel levels
- Watch for unusual noises
Address any warnings immediately. This can prevent bigger problems.
What is an OBD II Scanner and Why Should I Get One if I Have a Check Engine or Service Engine Soon Light On?
OBD stands for On-Board Diagnostic, and you can get one either at your auto parts store or online for anywhere between $30 to $200.
It doesn’t matter from which price range you purchase yours, they will all do the same thing. Some may even include a better, more detailed LCD screen.
Does having an OBD II scanner mean you never have to go to a shop? No, but you can at least discover the source of the problem for yourself.
If the fix is something easy, like an ignition coil, bad spark plugs, or even a gas cap, you won’t have to pay a mechanic to figure out what could have easily found instructions on how to do yourself.
Next step is to find the Diagnostic Link Connector (DLC). You can normally find it under the drivers-side dash close to the steering column, it looks like triangle appear port with 16 pins. If you cannot find it, refer to your manual for the exact location.
After you locate it, hook up the OBD II scanner with the ignition in the accessory position (do not start the vehicle). It will then ask for some information, like the Vehicle Identification Number (VIN), make, model, and engine type.
Depending on the scanner you buy, the procedures will vary. Nevertheless, you will want to get the scanner to the “codes” menu. You will see a couple of codes. Every code will start with a letter.
(P) for powertrain, (B) for body, (U) for undefined, and (C) for chassis. The letter will be followed by a series of numbers that will indicate the make of the vehicle, subsystem affected, and what the issue is.
It can be confusing at first if you have never used one before, but thankfully you can look up any specific code online to discover what it means. Here is a few of the most common.
FAQs.
Q: Is Service Engine Soon Bad?
Not exactly, the service engine soon light flashing is simply an indication that something is wrong.
Noticing the indicator lights coming on does not necessarily mean that your car will be packing up in the next few seconds. A range of issues can trigger the indicator light, but none of them is a dire situation.
Q: How Urgent Is The Service Engine Soon Light?
The “service engine soon” light is designed to warn you that the car’s sensor system has detected an issue with your vehicle’s performance. It is not an indication of an emergency. You can take it as a soft reminder to service your engine soon.
While the issues might be minor ones, it is in your best interest to fix them ASAP before they degenerate to worse conditions like engine sludge, for instance.
Q: What Is the Difference between A Check Engine Light And A Service Engine Soon Light?
Both of these symbols are used interchangeably because, in some cars, it is one or the other. However, there is a mild difference in what they do. The service engine soon light comes on there are mild issues with the way your engine is functioning.
On the flip side, when you see the check engine light, an immediate concern needs to be fixed ASAP. The check engine often comes on when your vehicle has any of the common engine problems.
Q: Can I Drive With The Service Engine Soon Light On?
Yes, you can. The service engine light lets you know that there are minor issues with the car and that you should service the engine as soon as you can. It is not an indication of an extreme situation so that you can drive with the light on.
However, you should not drive if you notice any of the other backlit symbols being on simultaneously with the “service engine soon” light being on.
Say the “check oil” or “check engine” indicator. It would be best if you have the vehicle checked once you see any of these indicator lights.
Q: Can Low Oil Cause Service Engine Soon Light?
Yes, it can. Your vehicle needs engine oil for the lubrication of the engine’s components. The oil levels have to be at an optimal level for the engine to perform at its best.
When the oil is below its optimal level the oil pressure drops. The ECM detects the drop in oil pressure, and the indicator light goes on.
Q: Can Spark Plugs Cause Service Engine Soon Light?
Your vehicle’s spark plugs are another reason why the service engine soon light on your dashboard might come up. The spark plugs are responsible for igniting the air/fuel mixture within the combustion chamber.
Faulty spark plugs will cause issues like poor acceleration, misfiring, starting problems, and increased fuel consumption. In some cases, the engine might not even start. Once any of these issues are detected by the car’s sensors, the service engine soon light is triggered.
Final Word
The presence of the “service engine soon light” is not the end of the world. It is simply an indication that you need to handle some minor issues that may have come up one way or the other. Although it is not a dire situation, you should get the issues fixed as soon as possible.
To do that, you could either go the DIY route using some of the tips we described in the article. You could also opt to get professional help. Whatever option you decide to take, resolve the issues before it degenerates into something worse.