kia check engine light on troubleshooting problem

Kia Check Engine Light On Troulbeshooting


Updated Thursday Jul 06, 2017


Kia Check Engine Light (CEL) (also known as Service Engine Soon) may turn on and stay on. This problem may be experienced by owners of Kia models such as Rio, Sorento, Sportage, Sout, Optima, Spectra Forte, Amanti, Sedona and other models will find this guide helpful. In this article, you will learn about the most common reasons why Kia check engine light can come on, and how to use an inexpensive OBD2 Scan Tool to read and clear the codes yourself. 

Normal Operation: The Check Engine Light should stay on when you turn the ignition to ON position and until you start the engine, after that the light should turn off. If the light continues to stay on, that means there is a problem and you need to get your car diagnosed. 

What does it mean when Kia Check Engine Light is on

kia check engine light onWhen your check engine light illuminates on your Kia vehicle, it means that the vehicle's Electronic Control Unit (ECU), or computer, which controls many aspects to your Kia's operation, finds a problem that it can not correct itself. The ECU stores a diagnostic trouble code (DTC) in its memory, triggering your check engine light to turn on your dashboard. For your Kia, it could mean any number of things - it may be something as simple as a loose gas cap, a problem with an incorrect fuel/air mixture, or something much more severe as an engine problem. 

Depending on the problem, there may be more than one error code stored. After the codes are read using an OBD-II scanner (see instructions below), a plan can be made to correct the problem.

Kia Check Engine Light Flashing

If the check engine light is flashing, it means there is a critical problem that needs to be addressed right away. If this ever happens when you are driving, pull over as soon as it is safe and call a towing company to take your car to a repair shop. When the check engine light is blinking, it is not safe to operate the vehicle.

Common Causes

Kia Check Engine Light On Common Causes

Gas Cap Loose

kia check engine light on due to loose gas capIt may sound trivial, but a loose gas cap, especially in Kia vehicles, can cause the check engine light to turn on. Many Kia owners have complained about the possibility of the sensor in the gas cap being too sensitive. To fix this problem, they replaced the existing gas cap with a one click model, making it almost impossible for you to leave it loose. Not only is the gas cap important for sealing off the fuel tank, preventing gas from evaporating, but it also helps to maintain the correct amount of fuel pressure within the system.

Spark Plugs

bad spark plugs trigger kia check engine light Spark plugs provide the necessary spark to ignite the air/fuel mixture within the engine. When they are dirty or they malfunction, you will experience reduced engine performance and poor fuel economy. Spark plugs need to be replaced every 60,000 miles or if you Kia has copper    

Oxygen Sensor 

o2 oxygen sensor trigger kia check engine light service engine soonOxygen sensors are located at various points in the exhaust system and will need to be replaced from time to time as part of regular maintenance. It measures the amount of unburned oxygen in the exhaust system. A malfunctioning oxygen sensor will cause an error code to set in the computer, causing the check engine light to come on. If the problem is ignored for too long, you will experience decreased fuel economy because the engine will burn more fuel than is necessary.

Catalytic Converter 

bad catalytic converterThe job of the catalytic converter is to convert carbon monoxide into carbon dioxide, which is then emitted into the atmosphere through the exhaust. When it malfunctions, it is usually due to another underlying problem, such as with the spark plugs, oxygen sensor, or other parts of the engine involved in creating the proper air/fuel mixture.

MAF Sensor 

how to reset check engine light on kiaThe responsibility of the mass airflow sensor is to regulate the amount of air coming into the engine so that the correct air/fuel mixture can be achieved, resulting in the most efficient engine operation. When it malfunctions, it will cause the check engine light to come on and the error code will store in the computer?s memory. A damaged MAF sensor will also cause damage to other engine/emissions components, including spark plugs, oxygen sensors, or catalytic converters. A malfunctioning MAF sensor will cause poor fuel economy and reduced engine performance.

Faulty Throttle Position Switch 

kia check engine light flashing bad throttle position switchA defective throttle position switch on Kia vehicles can cause the check engine light to come on. In this case, you may experience lack of power or poor acceleration. If your Kia has this problem it may trigger P0122 - Throttle Position Sensor / Switch A Circuit Low Input error code.The sensor can be easily replaced at home and is very affordable. Check out prices on Kia Throttle Position Sensor on Amazon. 

Kia check engine light turns on after you fuel

kia check engine light after putting fuel at gas stationMany Kia owners have mentioned online that their check engine light illuminates after filling up their gas tank, specifically after they top off the fuel level after the pump has automatically stopped. In older vehicles, topping off the tank beyond the automatic stopping point of the gas pump was not a problem, but in newer vehicles, and particularly in Kia, filling the gas tank up to the very top beyond when the pump automatically stops can flood the vapor canister. The vapor canister is designed to collect gasoline vapors and hold onto them until the vehicle can burn them instead of letting out the fumes into the atmosphere. It is connected to the fuel tank by a few vent hoses. Overfilling the tank - beyond the point when the pump stops - can force liquid gasoline into this vapor collecting device, which is not designed to hold liquid gasoline because the fuel deteriorates the charcoal components of the filter. It can't purge the liquid properly, so doing it will result in your check engine light turning on because of any number of evaporation or emission trouble codes being set in your vehicle?s memory.

Sometimes continuing to drive can solve the problem, but sometimes you may need to have your vapor canister filter replaced, as well as any additional fuel components that may become damaged when the charcoal bits and components get into other parts of the fuel system.

Kia Check Engine Light Stays On

Sometimes the check engine light will continue to stay on even after the problem has been fixed. This is a known issue in particular models of the Kia Rio. Many customers who own models of the Rio from the early 2000s have experienced a case of the check engine being on when there is nothing wrong with the car. This is a known issue with some models of the Rio and the fix may require the reprogramming of the transmission control module. According to multiple sources, software updates to fix this problem are most effective on later models of the Kia. This reprogramming can be completed at any Kia dealership.


How to reset Kia Check Engine Light

The simplest way to reset the check engine light yourself is to use the OBD-II scanner. You can use an inexpensive scanner such as the Autel MaxiScan OBD2 Scan Tool  which is a handheld unit or an ELM327 Bluetooth Adapter and your phone.  The scan tool plugs into the OBD-II port located underneath the steering wheel. This method applies only to Kia vehicles that are model year 1996 and newer.

kia sorento check engine light problems

Step 1

Locate the OBD-II port under the dashboard.

kia optima check engine light problems

Step 2 

Plug in the OBD-II code reader. 

kia optima rio sportage sedona check engine light problems

Step 3

Turn on the engine. Do not start the car. Scan and erase the fault codes. Codes can only be erased after you fix the underlaying problem. 

Reset Kia Check Engine light by disconnecting the battery

This method will not work on many newer Kia cars. It is a strategy that can be used to clear the check engine code from your vehicle's memory if you do not have an OBD-II scanner. 

  1. Disconnect the negative connection (black wire) from the battery. Leave it disconnected for five minutes.
  2. While the battery is disconnected, turn the key in the ignition to the ON position three consecutive times.
  3. Double check that the key is in the off position in the ignition.
  4. Reconnect the negative connection to the battery.
  5. Turn your key to the ON position and wait for 1 minute.
  6. Start your car as usual. Note that the check engine light will turn back on if the problem hasn't been fixed. 

FREE Check Engine Light/MIL Diagnosis

Many auto repair shops and auto parts stores such as AutoZone or PepBoys have OBD-II scanner tools which they can use to read your engine trouble codes for free. Using their services, they can retrieve your codes so that you can write them down and later interpret them. Sometimes, the repair shop employee may be knowledgeable enough about engine codes to at least inform you of the area of concern that the code is referring to.