The service engine soon light usually pops up to give you a friendly reminder that something’s off with your car.
Ignore it, and that friendly nudge can turn into an expensive issue.
But don’t worry!
We’ll explain what a “service engine soon” light means and why it turns on, so you can identify which car part needs a little love. We’ll also tell how it differs from the dreaded check engine light and how to turn it off.
This Article Contains:
- What Does a Service Engine Soon Light Mean?
- How Is the Service Engine Soon Light Different From the Check Engine Light?
- 3 Alarming Reasons Why Your Service Engine Soon Light Turns On
- Why Does Your Check Engine Light Come On?
- What Can You Do to Turn Off the SES Light and CEL?
What Does a Service Engine Soon Light Mean?
If you see the “service due” or “service engine soon” light on your car dash, it’s a reminder to take it for a check-up. It’s also called SES light and is usually red or yellow in color.
At first, the light will show a solid color, indicating your car just needs a scheduled maintenance check soon. But if ignored for long, it’ll start flashing, signaling you have a bigger issue that needs a qualified mechanic immediately!
Now, if the SES light sounds a bit like a check engine light — spoiler alert — it isn’t.
Let’s find out how.
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.
3 Alarming Reasons Why Your Service Engine Soon Light Turns On
Here are a few problems that might trigger the SES light:
1. Missed Routine Maintenance
The service engine soon light can come on when your engine oil, transmission fluid, or other liquids run low. It can also light up when you miss scheduled maintenance, such as fuel filter checks.
If the SES warning light turns on with an error code, check your owner’s manual to identify what part needs attention.
2. Loose Fuel Cap
A fuel cap or gas cap seals the tank to prevent vapor leaks and maintain pressure in the fuel system. A loose gas cap can let extra air into your fuel tank and cause the fuel vapor to escape.
This can affect the air-fuel ratio and make it difficult for your engine to run smoothly. As a result, your car’s computer may detect a problem and trigger the service engine soon light.
NOTE: If excess air enters the fuel lines, it can also trigger the check engine light.
3. Dirty Air Filter
Air filters should typically be replaced every 12,000 to 15,000 miles or about once a year.
But if you delay it, air filters can get clogged, restricting airflow to the engine and forcing it to work harder. In the worst case, harmful exhaust gases can leak inside your cabin, compromising the air you breathe.
Sensors like the Mass Airflow (MAF) or Manifold Absolute Pressure (MAP) detect this reduced airflow and trigger the SES light.
On the contrary, if the CEL pops up, it could mean some serious trouble brewing under the hood.
Why Does Your Check Engine Light Come On?
From exhaust system troubles to bad sensors, here are a few potential causes that can illuminate your check engine light:
1. Bad Spark Plugs or Wires
A spark plug ignites the air-fuel mixture in the engine to power the vehicle. Over time, spark plugs and wires can wear out, causing incomplete combustion or misfires.
The result?
Unburned oxygen and fuel can lead to increased emissions and poor engine performance. Your car’s computer will detect these issues and trigger the CEL light to alert you.
2. Faulty Mass Airflow Sensor
The mass airflow sensor (MAF sensor) is part of the emissions control system. It checks how much air enters the engine for combustion. However, when the sensor starts failing, it sends inaccurate data to the vehicle’s computer. This causes the engine to run too rich (excess fuel) or lean (insufficient fuel) and triggers the check engine light.
Ignoring the bad sensor can harm other vital parts. For instance, running rich causes unburned fuel to damage the catalytic converter, which will need immediate attention and can be an expensive fix.
NOTE: In a modern vehicle, issues with other emissions control system parts, such as the exhaust gas recirculation valve (EGR valve), catalytic converter, or oxygen sensors, can also trigger the CEL light.
So how can you turn off these warning lights?
Let’s find out.
What Can You Do to Turn Off the SES Light and CEL?
To switch off the indicator, you need to resolve the issues that trigger it. However, since these warning lights turn on for various reasons, it’s best to contact the nearest car service center and let a professional handle it.
Here are some common services they’ll perform:
1. Top-off or Refill the Car Fluids
The mechanic will check your engine oil using the dipstick to ensure it’s at the right level. They’ll also examine other fluids, such as coolant and transmission fluid, to ensure they’re close to the recommended level in the tank.
2. Tighten or Replace the Gas Cap
To address a loose fuel cap, the mechanic will unscrew and securely reattach it to the fuel filler neck. They’ll tighten it until they hear a clicking sound to confirm it’s properly sealed. But, if the fuel cap appears damaged or worn, the mechanic will replace it.
They’ll also disconnect and reconnect the negative car battery terminal to reset the warning light.
3. Inspect the Air Filter
The mechanic will carefully remove the air filter from its housing, ensuring no dirt or debris falls into the engine compartment.
They’ll then hold the filter up to a light source — if no light passes through, it’s clogged with dirt. The mechanic will also slightly press the filter’s folds to check if they’re brittle. In either case, they’ll swap out the air filter.
4. Check the Spark Plugs
They’ll remove the spark plugs and look for issues like carbon buildup, oil deposits, or physical issues like cracks and burned electrodes.
If the spark plug looks black, oily, or coated with soot, they’ll replace or clean it. They’ll also check the spark plug wires for visible damage, such as cracks, frayed sections, or burn marks on the insulation.
Additionally, they’ll test the spark plug wires using a multimeter to ensure they conduct electricity properly.
To test the wires, the mechanic will set the multimeter to the right ohms scale (50,000 or higher). Then, they’ll connect the probes to both ends of the wire and check the reading with the manufacturer’s guidelines.
They’ll replace the wire if the reading isn’t as per the guidelines.
5. Test the Mass Airflow Sensor
To test the MAF sensor, the mechanic will set the multimeter to voltage mode and connect the red probe to the MAF sensor’s signal wire. Afterward, they’ll connect the black one to a ground point, like the car battery’s negative terminal.
With the ignition on but the engine off, the multimeter should read between 0.5 and 1.5 volts. If the reading is outside this range, the MAF sensor will need a replacement.
Keep the Service Engine Soon Light Off with AutoNation Mobile Service
Hitting snooze on SES light-related issues can eventually result in poor engine performance. To turn it off, you’ll have to address it step-by-step.
Need a pro to turn off your SES light or CEL?
Let the experts at AutoNation Mobile Service take care of it for you!
We’re a mobile auto repair and maintenance service available seven days a week. All repair services come with a 12-month, 12,000-mile warranty.
Contact us to resolve the SES light issue or any other engine problem right from the comfort of your driveway.