All dashboard warning lights are equally important when it comes to your vehicle’s performance since modern cars have many of them.
A light to be acknowledged is the Service Engine Soon which can indicate maintenance or something else. This light will indicate a warning, yet a full diagnostic will have to be performed to identify the cause.
In this article, we examine Service Engine Soon, its leading triggers, and suggested options for corrective action. Additionally, we evaluate how to take action on the warning, and how to tell the difference between the Service Engine Soon and Check Engine lights.
Last but not least, we cover a few of the burning questions you might have as we near the end of the article so you can make the most informed decisions about servicing your vehicle.
What Does a Service Engine Soon Light Mean?
If your car indicates “service due” or says “service engine soon” on the dash, you can fairly gently take it to someone’s service.
The Service Engine Soon Light which is also known as SES Light, normally comes in red or yellow. In the beginning, that pending light will light up a color that means that a task has not been done with regard to maintenance due – more simply a check.
If you’re overdue and have not taken any action, then your car has a problem that is more serious that will need the attention of a skilled mechanic.
Although the SES light seems very much like a check engine light, so to story spoiler, it is not at all.
Let’s see how.
How is the Service Engine Soon Light Different from the Check Engine Light?
The check engine light (CEL), or malfunction indicator lamp, is usually more serious than the SES light. The CEL lights to warn that the vehicle has detected a more serious problem to avoid more severe problems, like a fuel tank leak or an engine misfire. Any issue that triggers the CEL usually needs to be responded to with urgency.
In contrast, the service engine soon (SES) light indicates the need for additional service, such as an oil change or filter change, etc. While these are considered a bit more important, they are not generally emergencies.
If you were wondering what to do when both the SES and CEL lights are triggered at the same time, you should pull over, turn off your vehicle, and have a qualified mechanic attend to whatever is wrong.
NOTE: On some vehicles, the SES light and the malfunction indicator lamp are one in the same and thus indicate an engine emergency.
You can also read this article for more information about what problems may cause a service engine soon light to appear.
6 Reasons Your Service Engine Soon Light Is On
Before anything else, a Service Engine Soon or Check Engine light comes on because an issue has taken place. The issue may be something simple that is easily corrected, or deep, complicated, catastrophic issues coming from your engine.
Let’s go over some of the most common ones.
#1. Loose/Faulty Gas Cap.
The first thing to check when the service engine light comes on is the gas cap to make sure it is firmly attached. If the gas cap is not on correctly or there is a minute crack in the gas cap, the fuel tank will then lose vapor or fumes that will cause the ECM to register a problem.
So even if the gas cap did not appear as bad as anything when you first checked it, consider using this scenario to temporarily bypass the check and repair of a weak gas cap gasket, which will obviously produce diminished fuel economy while producing greater gas emissions.
Surprisingly, whether you did not screw it on correctly the last time you went to get gas, or it has damaged, the answer is the same.
These steps should be performed with the engine off and at least half a tank of fuel. First, unscrew the cap and then reattach the cap. As previously mentioned, it usually takes a couple of cycles before the light goes off, and yes, the engine does have to be on and off for a bit.
If you noticed that the indicator has not turned off, at least 30 minutes to an hour after driving, it may be worth buying a new gas cap at your local auto parts store for about 10 bucks.
If a couple of general cycles have been done with no light turning off, there is another problem that needs to be checked.
#2. Scheduled Servicing Items/Low Fluid Levels.
It is not alarming if you are a week or two past due date for an oil change, however if the oil have come to a critically low level, then this will set off an alert. Your scheduled maintenance items like an air filter when excessively dirty will throw the whole system out of balance.
If you are using a car from a specific Make of vehicle, this will mean that your maintenance items along with the check engine, may also give you a check engine oil light, the check low coolant light, or a tire pressure light.
#3. O2 Sensor Failure.
The engine is capable of working optimally. But many things need to be monitored to make that happen: mass airflow sensor, engine speed sensor, spark knock sensor, and coolant sensor. If something happens that puts an engine’s optimal capability in jeopardy, many things can happen.
Next is O2 sensor. The O2 sensor measures the amount of oxygen in the exhaust fumes from the engine. If there is too little oxygen, the engine is ‘running rich’, while too much oxygen results in an engine that is ‘running lean’.
An O2 sensor problem will typically turn the Service Engine Soon indicator on. This happens because the O2 sensor is not able to accurately measure the correct fuel-air balance in the combustion chambers.
This will cause the indicator to turn on. In addition to the indicator light, the affected vehicle will have poor fuel economy, and misfire, or a rough idle.
#4. New Spark Plugs Needed.
The spark plug is a small part responsible for igniting the air and fuel in the combustion chambers of your engine.
You will probably need new spark plugs when you see a reduction in mileage, reduced acceleration, miss firing, difficult engine starts, rough idle or Service Engine light (you guessed it).
Old copper spark plugs would only last about 30,000 miles, but newer plugs such as platinum or iridium-tipped plugs can last up to 100,000 miles or more. If you let them go for too long your engine can stop entirely.
This is a good reason to replace them preemptively at the first sign of trouble since the plugs are only $10 apiece, and with labor you should get all of them replaced for less than $250 at an auto repair shop.
#5. Mass Airflow Sensor Malfunction.
The mass airflow sensor sends information to the ECM about how much fuel is needed based on how much air the engine is getting.
Diagnostic symptoms include a start issue, stalling, a rough idle, or hesitating when accelerating. If it continues to run however, the motor will eventually show you a Service Engine Soon light.
Although you can drive the car with a malfunctioning mass airflow sensor, it is certainly better to not do it for too long. Neglecting this can cause damage and result in a costly repair by destroying your catalytic converter and O2 sensors.
In this case the total costs can average somewhere around $200 to $400 with labor and depend on whether you go aftermarket part or OEM.
#6. Faulty Catalytic Converter.
A combustion engine works using power and gas or diesel, which is a petroleum product, by burning it. If it was pure petrol, then the only byproducts would be carbon dioxide and water.
However, those fuels have are up to 150 more chemicals, increasing the number of pollutants by magnitudes.
This allowed the pistons to move so the shaft could spin and those chemicals can now be burnt to make electricity.
Like any process, there are several moving parts that must be able to operate in conjunction at the same time to produce the final product.
This explains why older vehicles are typically worse than newer models for fuel efficiency.
A catalytic converter facilitates the replacement of these emission exhaust gases, so it will tend to have problems sometime.
If you get a Service Engine Light with the other issues on this list, such as the temp gauge in the red, low performance and lower RPMs and fuel economy it may be advisable for a professional service in regards to your catalytic converter.
A new catalytic converter can cost up to $2000 to replace on new cars. That can make it hard to justify not paying attention to your engine when it starts presenting the mildest issues.
Let’s think about what you can do now that you know about some common causes for the Service Engine Soon light.
Why Does Your Check Engine Light Come On?
The following are a handful of issues and conditions that may cause your check engine light to illuminate:
#1. Bad Spark Plugs or Wires.
Air and fuel are combined and burned in the engine via a spark plug in order to power a vehicle. If you have used a vehicle for an extended period of time, the plugs and wires may be worn out, and misfires or explosive combustion will occur.
If the combustion process is not efficiently burning the oxygen and fuel, your vehicle will poorly run and spew waste fumes. If there is too much fume emissions, it will be well above compliance levels.
The vehicle’s computer synchronizes these issues and therefore the check engine light or CEL light will be illuminated for you.
#2. Bad Mass Air Flow Sensor.
A mass air flow sensor is a part of the vehicle’s emissions control system. The mass air flow sensor monitors air flow into the engine for combustion.
A sensor that cannot read air flow correctly means it is sending wrong data to the computer. The vehicle could be running rich (too much fuel) or lean (not enough fuel) which means the check engine light or CEL light will activate.
Ignoring the sensor problems is sure to cause issues in other critical components. If the vehicle is running rich, for example, unburnt fuel (too rich) will destroy the catalytic converter – which is in itself has significant cost. If you don’t repair damage, it could cost you big money.
NOTE: Modern vehicles may have other parts of the emission systems that may cause the check engine light or CEL light alone to be triggered such as in the exhaust gas recirculation valve, catalytic converter or oxygen sensor.
What Should I Do If My Service Engine Soon Or Check Engine 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.
What Can You Do to Turn Off the SES Light and CEL?
A diagnostic scan will identify the reason for the issues, as there may be one or several issues in total. It is a fair amount of work because of the knowledge involved with a vehicle’s computer management, so you could need a good automobile service professional for assistance.
Here are a few typical tasks they will do:
#1. Top Off or Change car fluids.
A mechanic will check the engine oil, by using a dip-stick, and confirm the engine oil is full on the dipstick.
When re-filling the tank and confirming fluids such as coolant and transmission fluids, will be in an acceptable range in the tank.
#2. Tighten or Change Gas Cap.
When putting on the gas cap, the mechanic would have turned the cap clockwise until the car made a purring sound, indicating it was a tight seal.
If the cap is cracked, broken, or carted like the rest of the fuel tank, they could apply a more reliable gas cap. The light can also be reset by taking the negative terminal off and back on the battery, to free the code.
#3. Check the Air Filter.
The next procedure would be for the mechanic to safely free the air filter, with as little debris as possible going into the engine compartment.
They then would check to see if the filter was dirty at all by holding it up to the nearest light source to measure if any light passes through it. If no light shined through, they would know for sure that the filter was definitely clogged with dirt. Either way, they normally would install a new air filter.
#4. Check the spark plugs.
The spark plugs would be also taken off for checking for countless issues such as; carbon builders, oil on the spark plugs subject electrodes that have been burnt, and cracks or signs of damage.
Burnt electrodes would also appear black, oily, or encapsulated with soot; and would not only just be cleaned or changed out, they would also have to check the spark plug wires for major damage which has to be no cracks, theft, burn scars on insulation.
The remaining other wires should be checked with a multimeter to determine whether showing voltage as it should.
The multimeter would first need to be set up for the correct ohms scale – such as 50,000 or up. They would attach the probes to both ends of the wire and perform checks along the way till finding the evidence on what the sub check guideline should be as recommended by the manufacture.
If evidence does not match guideline, they than have to replace with all-new wires.
#5. Check the mass airflow sensor.
The last thing would be to check the mass airflow sensor to see how efficient it is operational.
The mechanic should: set the multimeter to voltage mode, and attach the probes; the red would be attached to the signal wire of the mass airflow sensor, and the black would be attached to ground (which is normal at the negative terminal of the battery).
The multimeter should read between 0.5 volts – 1.5 volts with the ignition on, but engine off. If the voltage is less than 0.5 volts or greater than 1.5 volts, the sensor must be replaced.
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.
Feeling Better About That Service Engine Soon Light?
No one ever wants to find out there is an issue with their vehicle. That being said, even though an Service Engine Soon or Check Engine light is never a good sign, don’t panic, it doesn’t always mean you have a catastrophic problem, it simply means you have found a notification that indicates you need to check on your vehicle.
If you find out what the issue is when it first appears, and get the problem fixed before it becomes a costly problem, you will save yourself time and money, and ultimately feel much better about your vehicle. on the road to live another day.