Blog Car Care Advice 12 Common Causes of An Active Hyundai Check Engine Light
Car Care Advice

12 Common Causes of An Active Hyundai Check Engine Light

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The Check Engine Light (CEL) on Hyundai Motor Group vehicles can be worrying. But it’s manageable once you know what to do

But what triggers the Hyundai CEL?
And how do you reset the warning light?

There are multiple reasons why the Hyundai Check Engine Light comes on. We’ll walk you through them and what to do next.

This Article Contains

Let’s dive in.

12 Common Causes for the Hyundai Check Engine Light

The issues below can affect your engine’s performance and thus trigger the Check Engine Light:

1. Loose Gas Cap

A loose, broken, or missing gas cap can cause fuel vapors to escape and reduce the fuel pressure in your engine. This reduces fuel efficiency and triggers the Check Engine Light. Tightening or replacing the gas cap can reset the CEL.

2. Failing Catalytic Converter

The catalytic converter in your Hyundai vehicle converts carbon monoxide in the exhaust fumes into safer components before releasing it into the atmosphere. A damaged or failing catalytic converter could lead to decreased engine performance and gas mileage, which activates the engine light. If you drive with a failing catalytic converter, you’ll risk engine misfires and overheating, which can lead to costly repairs.

3. Spark Plug Issues

A faulty spark plug or spark plug wires could cause a misfire, triggering the Check Engine Light. Plus, fouled spark plugs or frayed spark plug wires can prevent your car from running altogether or can lead to reduced fuel economy and engine performance.

4. Faulty Oxygen Sensor

The oxygen sensor (O2 sensor) helps the Engine Control Unit (ECU) regulate the engine’s air-fuel ratio. However, a faulty oxygen sensor can cause the vehicle’s ECU to supply the engine with the wrong fuel ratio.

Why is this bad? 
An engine running on a lean fuel mixture is at risk of total engine failure, and when there’s too much fuel, it’ll create excessive smoke and odor. This reduces gas mileage and triggers the Check Engine Light.

5. Bad Mass Airflow Sensor

The mass airflow sensor is in charge of measuring the amount of air that enters the engine. If your Hyundai vehicle has a starting issue, rough idle, or you feel a sudden change in the throttle pedal position, you might have a bad mass airflow sensor. This can lead to poor fuel economy and engine misfires, activating the Check Engine warning light

6. Vacuum Leaks

The vacuum hose regulates the pressure inside the engine, but it can dry out and crack, causing vacuum leaks. This leak can affect the combustion process and lead to engine failure, illuminating the Hyundai Check Engine Light. 

In addition to the common causes mentioned above, the CEL can also come on for other reasons. 

Other Causes for the Check Engine Light

  1. Engine oil leaks and severely low engine oil can cause both the CEL and oil light to illuminate.
  1. A weak battery can also affect your engine’s performance and trigger the battery and engine light.
  1. A faulty ECU or ECM (Engine Control Module) can lead to poor engine performance and trigger the Check Engine Light.
  1. An Exhaust Gas Recirculation (EGR) system malfunction can activate an EGR-related engine code and the Hyundai Check Engine Light.
  1. A malfunctioning thermostat can lead to overheating, decreased engine performance, and an illuminated Check Engine Light.
  1. A fault in the Evaporative Emission Control (EVAP) system can cause fuel to be released along with exhaust fumes. This can lead to low fuel efficiency, decreased engine performance, and an active CEL. 

But what are you supposed to do when the CEL comes on? 
Let’s take a look.

What to Do if the Hyundai Check Engine Light Comes On?

The Check Engine warning light on a Hyundai Elantra or other Hyundai Motor Group vehicle can light up in three ways.

A. Illuminates Under Certain Circumstances 

If the Hyundai Check Engine Light comes on intermittently, note any changes to your vehicle’s performance. This is to give you a heads-up about a potential part failure. You can drive when the light comes on in such situations. However, it’s best to immediately head to the nearest Hyundai service center to prevent further stress on the engine.

B. Steady Yellow Light

A steady yellow or amber engine light indicates an engine problem. It tells you that an issue or fault code needs attention but isn’t fatal (loose gas cap, frayed O2 sensor wires, etc.). It can also mean that you have a service due.

If the engine light glows yellow, drive to a professional mechanic or back home and schedule a mobile mechanic service. A check engine light diagnosis should be done soon to avoid other costly repairs.

C. Red or Flashing Check Engine Light

When you come across a red or flashing check engine light, this means there’s a major underlying issue that needs immediate attention, and you should immediately stop driving. Park in a safe place and call for a tow truck to get your car to the closest Hyundai Service Centre.

Next, let’s see how to reset the CEL once a mechanic resolves the issue.

How to Reset a Hyundai CEL? 

The Hyundai Check Engine Light will automatically shut off once the underlying issue or fault code has been resolved. This can also take over 20 to 40 minutes while driving. However, if you’ve driven for quite some time and the light is still on, you should return to the service center to get the light looked at. 

A professional mechanic would use an OBD II scanner tool to recheck for an unresolved engine code in the system. If no other diagnostic trouble code is found, your mechanic will manually turn the engine light off.

Here’s how they’ll do it:

Worried about the Check Engine Light diagnosis cost?
Read on to find out.

How Much Does a Hyundai Check Engine Light Diagnosis Cost?

A Hyundai Check Engine Light diagnosis can cost between $88 to $111 for a Hyundai Elantra or any other Hyundai make — for new vehicles or pre owned vehicles. This is because the Hyundai CEL doesn’t tell you what’s exactly wrong with your car.

Hence, the diagnosis and repair costs could vary depending on the issue. For example, fixing a faulty or loose gas cap would cost less than replacing a bad oxygen sensor or failing catalytic converter. The mechanic would also need to use an OBD II scanner to conduct a full diagnostic check to find the exact trouble code that’s causing it.

Final Thoughts

The Check Engine Light in your Hyundai Vehicle indicates an EVAP system or engine problem, like a worn oxygen sensor, vacuum leak, or faulty catalytic converter. If you see this warning light on your dashboard, it’s best to get it checked out immediately by a professional like AutoNation Mobile Service!

Contact us today for a Check Engine Light diagnosis, and our expert technicians will fix your Hyundai right in your driveway.