Service Engine Soon Light: What It Means and How To Fix It

With so many dashboard warning lights on today’s cars, it’s important to know what each one means. The Service Engine Soon Light is one that should always be paid attention to, even if it’s only telling you that maintenance is due. In reality, you won’t know what it is alerting you about until you perform a complete diagnostic. 

In this guide, we look at the meaning of the Service Engine Soon light and its top causes. We also evaluate how to fix the alert and help you see the difference between the Service Engine Soon and Check Engine Lights. Towards the end of the article, we answer a few of your top questions, so you can take better care of your vehicle. 

What Does The Service Engine Soon 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. 

Service Engine Soon Vs. Check Engine Light

The differences between the two lights are how they look and the type of problem that occurs. When the Service Engine Soon light comes on, you know it’s time for regular maintenance or there’s a minor mechanical problem that requires your attention. The Service Engine Soon light is written out in words.

On the other hand, the Check Engine Light includes a picture that resembles a motor. With some models, you see the words “Check Engine” The problems associated with this warning include varying degrees of severity. With a solid Check Engine Light, there could be a mechanical problem that requires attention as soon as possible. This light also comes on for some minor problems that aren’t a big deal. 

When the Check Engine Light is blinking, it means catastrophic damage can occur if you keep driving, requiring you to pull over and turn the car off. You should never ignore the blinking light.

Causes Of Service Engine Soon Light

When the Service Engine Soon Light comes on, you know that it’s either time for regular maintenance or a fault needs to be corrected. Here are some of the most common causes of a service engine soon light:

1. Loose Or Faulty Gas Cap

If you’ve just filled up the tank, you may not have put the gas cap back in place. When the gas cap is loose, it sends a signal to the ECU, mimicking a leak in the system. This would be the simplest problem to rectify.

The same problem occurs if the gas cap gets cracked or broken. Additionally, if you leave the gas cap behind, the open system will cause a warning light on the dashboard. While there may not be any performance issues from driving without a gas cap, you want to have it fixed as soon as you can.

2. Low Fluid Level

Regular maintenance includes changing the fluid and flushing systems. Oil changes should occur every 3,000 to 10,000 miles, depending on what type of oil you use. At the same time, the oil filter should be changed. Additionally, the coolant and transmission fluid should also have regular changes.

If one of these services is due or overdue, the warning light might appear on the dashboard. It’s not because the system knows when a fluid change is needed, but more likely because the old, contaminated fluid is leading to other problems. Reference the maintenance schedule to determine what is supposed to be done. 

3. Scheduled Service Overdue

The fluid changes aren’t the only maintenance tasks that should be performed. The manufacturer also outlines when air filters should be changed, spark plugs should be replaced, and brake pads should be checked.

Your Service Engine Soon light might come on as a reminder that service has been neglected. Again, it’s not because the system has an idea of when service should be performed, but it does recognize when problems are created as a result of neglect. For example, if you don’t change the spark plugs and one becomes fouled, the system is going to tell you that an issue is happening. 

4. Contaminated Gas

There’s no way of knowing if the gas at your local filling station is any good. For this reason, it’s possible that you put bad gas in your car. While it’s less possible when visiting a top-tier fuel station, it can still happen. Otherwise, you may have let the gas sit in the tank too long, where it can also go bad.

When the car has bad gas in it, the Service Engine Soon light can come on. You may also have trouble starting the engine or notice a rough idle. In extreme cases, there will be pinging sounds and the engine will stall. 

5. Faulty Engine Sensor

With the engine, there are multiple sensors designed to keep everything running efficiently. From the oxygen sensors to the mass airflow sensor, the ECU is constantly analyzing data and making adjustments. If one of these sensors fails, it’s possible that the Service Engine Soon light may come on.

Additionally, some cars have a Check Engine Light instead for these problems. For that reason, either light is possible with a defective sensor. 

How To Fix A Service Engine Soon Light

Once the Service Engine Light comes on, you want to make time to fix the problem as soon as possible. By neglecting the light, you could allow larger problems to manifest, thereby causing higher repair bills in the future.

With a few minutes, you can figure out what’s going on with your car. Here are some of our suggestions.

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. 

Conclusion

It’s always alarming to see a warning light on the dashboard. The good news is that you don’t normally need to panic over the Service Engine Soon light. While you should take care of the problem as soon as you can, there’s no reason to pull over on the side of the road. Instead, drive carefully back to your home and start diagnosing the problem for a quick repair.

If you choose to neglect the Service Engine Soon light, you can expect bigger problems to arise. A minor problem can lead to failure in other areas, with parts that could be expensive. An example of this is when you drive with bad spark plugs. This simple $100 fix could easily turn into $2,000 if the fouled plugs damage the catalytic converter. Take care of your car and it will provide you with more years of service. 

Learn more:

• Check Engine Light After Oil Change – Causes & How to Fix
• How to Change the Oil in Your Car (5 Easy Steps)
• 11 Car Maintenance Tips (Extend the Life of Your Car)