Each dashboard warning light is of equal importance when it comes to understanding your vehicle, and the modern car is equipped with many.
A warning that must be acknowledged is the Service Engine Soon Light, be it for maintenance or something else. The light will show an alert, but will require a full diagnostic to be performed to know the triggering cause.
In this article, we examine the Service Engine Soon, its leading factors, and suggested corrective actions. In addition, we evaluate how to resolve the warning as well as distinguish between the Service Engine Soon and Check Engine Lights.
Lastly, we address some of the burning questions you have towards the conclusion of the piece so that you can maintain your vehicle in a better manner.
What Does a Service Engine Soon Light Mean?
If your vehicle’s dashboard displays “service due” or “service engine soon,” gently take the vehicle to a service center. Also known as SES Light, it tends to come in two colors, red and yellow.
Initially, that light will illuminate in a particular shade, signaling that a particular maintenance task is overdue for execution, more in this case, a simple check.
If left for too long, it indicates that more serious problems exist, which will require the immediate attention of a skilled mechanic.
While it may seem that the SES light is very similar to a check engine light, as the saying goes, story spoilers, it’s nothing of the sort.
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 generally more critical than the SES light. It lights when your vehicle detects more critical problems, to avoid deeper issues such as fuel tank leaks or engine misfires. Issues that trigger the CEL typically require an urgent response.
Meanwhile, the service engine soon light indicates more maintenance actions, such as oil changes or filter changes. These can be considered slightly more important, but they also cannot be considered urgent.
Wondering what to do if both the service engine soon light and check engine light come on simultaneously?
You should stop the vehicle, switch off the engine, and have a qualified mechanic deal with the underlying issue.
NOTE: On some models, the SES light and the malfunction indicator lamp are the same and therefore indicate a severe condition with the engine.
Next, read this article further to discover what problems can lie behind a service engine soon light.
6 Alarming Reasons Why Your Service Engine Soon Light Turns On
As previously noted, a Service Engine Soon or Check Engine light comes on when an issue arises. This can vary from being simple and easily fixable to deep, complicated, catastrophic issues with your engine.
Let’s go over some of the most common ones.
#1. Loose/Faulty Gas Cap.
The very first step to take when the service engine light turns on is to inspect the gas cap and ensure that it is on properly. If it is not fitted properly or there is a small gas cap crack, it can result in the loss of fuel vapor, which would cause the ECM to think that there is, in fact, an issue.
So even though the gas cap itself did not seem that bad at first, considering using this will bypass the checking and fixing of a weak gas cap gasket, it is clear that if not fixed, a drop in fuel economy will happen along with a rise in gas emissions.
Surprisingly whether you did not screw it on correctly the last time you went to get gas, or if it truly is broken, the answer is the same.
These steps should be performed with the engine off and having at least half a tank of gas. First, the cap has to be unscrewed and then put back on. As stated before, it usually requires a few recycles before the light goes off, while having the car turned on and off for a bit.
If you noticed that it has not turned off for at least 30 minutes to an hour after driving, you might want to consider purchasing a new one for about 10 dollars from your nearby auto parts shop.
If the indicator light does not turn off after a while, there is another problem that needs to be looked into.
#2. Scheduled Service/Low Fluid Levels.
It’s not concerning if you’re one week or two weeks overdue for an oil change; however, if you are critically low on oil, then that can set off an alert. This also applies to maintenance items like an air filter that, if too dirty, can completely throw the system out of balance.
If you are using a car from a certain make, maintenance items alongside the check engine will likely turn on other indicators such as the oil light, the low coolant light, or a tire pressure light.
#3. Oxygen Sensor Failure.
The engine is built to run at an optimal level. Several elements like mass airflow sensor, engine speed sensor, spark knock sensor, and coolant sensor need to be monitored. If a problem occurs that puts an engine’s optimal capability at risk, many things can go wrong.
Next is the O2 sensor, which checks the amount of oxygen present in the exhaust fumes emitted from the engine. If the oxygen level is too low, the engine is ‘running rich’, while if it is too high, the engine is ‘running lean’.
An O2 sensor problem will usually cause a Service Engine Soon light to turn on. The reason for this is the O2 sensor’s inability to accurately measure the correct fuel-air balance in the combustion chambers.
This will make the indicator light turn on. In addition to this indicator, the affected vehicle will suffer from lower fuel economy, misfiring, or rough idling.
#4. New Spark Plugs Needed.
Spark plugs are responsible for igniting the air and fuel mixture in the combustion chambers of your engine. You may need to replace them when you observe a lack of mileage, diminished acceleration, misfires, difficult starts, a rough idle, or a Service Engine light (you guessed it).
Old copper spark plugs would only last about 30,000 miles, but newer ones like platinum or iridium-tipped can last up to 100,000 miles, if not more.
If you neglect them for far too long, your engine might stop running altogether. Therefore, this gives you a good reason to preemptively replace them at the first suspicion of problems, considering the parts themselves are only $10 each, and with labor, you should be able to replace them all at a local shop for less than $250.
#5. Mass Airflow Sensor Failure.
The mass airflow sensor tells the ECM how much fuel it should use based on the air it is receiving. Diagnostic symptoms include issues with starting the engine, stalling, or idling, or hesitating when accelerating the vehicle. Should this persist, the motor will notify you with a Service Engine Soon indicator.
Although one can move about with a malfunctioning mass airflow sensor, long periods of doing so are strongly discouraged. Neglecting it can be damaging and result in expensive repairs by destroying your catalytic converter or O2 sensors.
The total expenses in this case will average around $200 to $400 with labor, and depend on whether aftermarket or OEM components are chosen.
#6. Faulty Catalytic Converter.
A combustion engine functions by using power and gasoline or diesel, which is a petroleum product, by burning it. If it is pure petro, the only byproducts would be carbon dioxide and water.
However, these fuels contain up to 150 additional chemicals, which greatly increase the number of pollutants.
This allowed the pistons to move so the shaft could spin, and these chemicals can now be burnt to create electricity.
As is the case in any process, several steps must be performed in parallel to produce the end product.
This lays out the reasoning for why older vehicles tend to be less efficient than newer models when it comes to fuel efficiency.
A catalytic converter is responsible for replacing these emission exhaust gases, which is why it will tend to have problems sooner or later.
If your Service Engine Light comes up with the other problems on the list, such as the temp gauge in the red, low performance, or lower RPMs and fuel consumption, it may be best to see a professional for your catalytic converter.
It can cost up to $2000 to replace one on new cars, and that makes it easy to justify paying more attention to the health of your engine when it starts showing the mildest issues.
Let’s explore what actions to take now that you have an understanding of some of the main causes why the Service Engine Soon light turns on.
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
The air and fuel mixture in an engine is burned to provide power to a vehicle, and it is done through a spark plug. If a vehicle is used for too long, there’s a possibility that the plugs and wires are worn out, which means that combustion or misfires will happen.
If there is no proper burning of oxygen and fuel, your car’s engine will perform poorly and emit waste fumes, leading to excessive fumes breaching regulatory limits. Your car’s computer synchronizes these issues, and the CEL light will be turned on so that you can be alerted.
2. Faulty Mass Airflow Sensor
This sensor is also a part of the vehicle’s emissions control system. It monitors the quantity of air that goes into the engine for combustion. When a sensor fails, it to the computer the wrong data. Because of this, the vehicle may be rich (too much fuel) or lean (too little fuel) and trigger the check engine light.
Disregarding the faulty sensor is bound to affect other critical components. For example, being rich means unburnt fuel will damage the catalytic converter. Damaging and will require urgent attention. Unfortunately, this could be quite costly to repair.
NOTE: On modern vehicles, concern with other parts of the emission systems, such as the exhaust gas recirculation valve (EGR valve), catalytic converter, or oxygen sensor, may also activate the CEL.
How can these alerts be turned off?
Let’s see.
What Can You Do to Turn Off the SES Light and CEL?
A diagnostic scan will highlight the underlying issues, as there may be multiple factors causing the warning light to illuminate. Since this requires adequate knowledge of the vehicle’s computer management system, it is recommended to seek the assistance of an automobile service professional.
Here are some common tasks they will carry out:
#1. Top off or Refill the Car Fluids.
The mechanic should use a dipstick to check if the engine oil is at the required level. They will also check if fluids like coolant and transmission fluids are within acceptable ranges in the tank.
#2. Tighten or Replace the Gas Cap.
While putting the gas cap on, the mechanic will turn the cap in a clockwise direction until the car makes a purring sound, signifying it is a tight seal. If the fuel cap is cracked, broken, or looks worn, the mechanic can replace it with a more reliable gas cap.
The light in question can also be reset by disconnecting then reconnecting the car battery’s negative terminal.
#3. Inspect the Air Filter.
A mechanic will take the necessary steps to carefully detach the air filter, ensuring no contaminants make their way into the engine compartment.
From there, they will check if the filter is too dirty by holding it up to a light source. In case no light passes through, they will know the filter is indeed clogged with dirt. In either case, they will replace the air filter.
#4. Check the Spark Plugs.
The spark plugs will be removed and examined for many problems, including carbon buildup, oil deposits, or damage such as cracks to the electrodes that have been burned.
Burnt electrodes will also be present if the spark plugs appear black, greasy, or encapsulated in soot, and they’ll be cleaned or replaced. Inspection of the spark plug wires will also be needed for severe damage, which consists of cracks, fraying, or burn scars on the insulation.
The other wires will require the use of a multimeter to measure whether they are carrying voltage as needed.
The mechanic will first set the multimeter to the required ohms scale, which is 50,000 or higher. The probes will then be connected to both ends of the wire, and the reading will be checked against the guidelines provided by the manufacturer.
If guidelines are not met, the wires will then be replaced.
#5. Test the Mass Airflow Sensor.
To test the operational efficiency of the MAF sensor, the mechanic will preset the multimeter to voltage mode and attach the red probe to the signal wire of the MAF sensor. The black probe will be connected to ground, typically the negative terminal of the battery.
The multimeter must indicate a value between 0.5 volts and 1.5 volts while the ignition is on and the engine is off. Volts below or above this range would require the sensor to be replaced.