Why Is My Check Engine Light Still There?

Photo courtesy of Wikimedia Commons Images by Wikiuser100000

You’ve got a check engine light warning on your dash. Now what? You must be worried. And that’s okay, because clearly your car is in trouble. But how serious is the problem?

Can you trust your car to get you to your next destination? You’re not even sure if you should pull over, keep driving or call the tow truck!

Calm down. We’re here to help. We’ll tell you how to handle this situation like a pro. And avoid causing further damage to your car or any unnecessary expenses.

What Does the Check Engine Light Mean?

Your car has diagnostic systems to help it run smoothly and detect issues that need to be addressed.

Examples include the ABS brakes system, the engine diagnostic controls, the emissions systems, among others.

All these systems can cause the check engine light to come on. The reason could be a simple harmless issue or a major complicated issue that can be termed as an emergency.

Let’s have a look at the typical issues that can cause your car dash icons to light brighter than a Christmas tree.


A thermostat is a bimetal component that’s part of the cooling system. As the coolant flows the thermostat regulates the engine temperature.

A stuck open thermostat prevents the engine from reaching its optimal temperature necessary for proper operation. Similarly, a stuck closed thermostat causes your car engine to overheat.

If the temperature gauge drastically shots to the red zone, the check engine light comes on.

Solution: Replace the thermostat. Or, if the engine has overheated let a mechanic inspect it. If the head gasket is damaged, or any other component, replace it.

Emissions Sensors

Emissions sensors help your car run a cleaner and greener engine. As a result, the environment is protected against harmful emissions which obviously have dire effects on mother earth.

Here are the components that help the emission system run clean:

  • Exhaust gas recirculation system (EGR)
  • Purge control system
  • Evaporative emissions, etc.

Notably, the purge control valve and the purge solenoid are prone to failure. Once these parts get stuck, the check engine light will come on – constantly.

Solution: Repair of faulty emission sensor parts is affordable. Therefore, just carry out the inexpensive repair.

This is not an emergency repair. No further damage will be done to your car, meaning you can continue driving.

But remember the harmful emissions are affecting your environment.

Related: Car Warning Lights Resource Centre

Oxygen Sensor

A faulty oxygen sensor is the most common cause for the check engine light to come on. Most vehicles have two or more oxygen sensors both upstream and downstream of the engine.

Oxygen sensor measures emission in the exhaust and uses those readings to do the real-time adjustment in engine performance.

Signs of a faulty oxygen sensor are a decline in fuel efficiency and the engine performing poorly. Also, the engine can run lean eventually cause long-term debilitating engine damage.

Fuel Cap

Sounds like an afterthought, but it isn’t. A loose fuel cap or one that doesn’t seal well is notoriously known to cause the check engine light to come on. If you’ve just filled up and the check engine light comes on, this could be the cause.

Apart from preventing fuel spillage, a fuel cap also seals the filler neck enabling the fuel system to remain pressurised. That’s how your car’s diagnostic system checks for leaks.

Solution: When you get the warning light, inspect the fuel cap. If loose, tighten it properly. But if you notice it doesn’t seal well or it’s worn off, just buy a new one at your nearest auto shop.

It will set you back around $27. But, you’ll save a lot on fuel.

Catalytic Converter

Repairing a failed catalytic converter or buying a new one is one of the most expensive auto repairs. However, if you do regular car maintenance, you can prevent your catalytic converter from failing.

The catalytic converter superheats unburned compounds flowing through the exhaust pipe.

This process transforms the pollutant hydrocarbons, nitrous oxides, and other chemicals into less harmful elements such as carbon dioxide and water.

Solution: Have a certified mechanic replace or repair (depending on damage extent) your catalytic converter.

Ignition System

A faulty ignition system could also be the reason your check engine light is flashing.

The ignition system is comprised of:

  • Spark plugs
  • Ignition coil
  • Ignition cables

These are the ignition system parts that work simultaneously to ignite the fuel in the engine cylinders. When they malfunction, they cause an engine misfire!

A misfire simply means the fuel didn’t ignite properly or there was no spark produced.

When the engine misfires, the check engine light comes on. And if the misfire persists, the check engine light will start flashing meaning it’s an emergency.

Solution: It is crucial that you do a repair of the ignition system immediately. Otherwise your car will stall when you least expect it.

Plus, the faults in the ignition system may lead to more complicated issues such as a flooded engine or worse still a failed catalytic converter.

ABS Concerns

The anti-lock braking system (ABS) is part of your car systems that are constantly monitored as you drive. The ABS monitor your car wheels to ensure they are turning at the same speed.

When on a slippery terrain, the ABS system will use the brakes to keep the car under control.

The ABS system concerns include:

  • The faulty stability control system
  • ABS hydraulic control unit leaking thus affecting power brakes
  • Faulty ABS control module compromising your entire braking system
  • A faulty wheel speed sensor leading to lost traction control and ABS brake issue

Solution: Fixing the ABS system is very costly. Sometimes a simple wiring repair can fix the issue.

Other times you’d have to replace the wheel hub that houses the ABS wheel sensor. Or, you may need to change the module/control unit.

MAF Sensor

MAF sensors report the amount of air being injected into the Powertrain Control Module (PCM). The PCM then uses that data to work out the engine load.

The Mass Air Flow Sensor (MAF) can cause a flashing check engine light. The MAF is a delicate sensor that can trigger the warning light even with a slight malfunction. There have been reports of flies getting sucked into the air filter and getting stuck on the MAF sensor, causing an error signal to be sent to the computer.

Solution: In most cases a simple procedural cleaning of the MAF sensor can solve the issue. But at times, you may need to replace the MAF sensor or repair – quite affordable.

But until you carry out the repair, you will have an unreliable engine, and a car that consumes more fuel and potentially stalling due to erroneous air metering.

How to Reset the Check Engine Light

Once you have done the repairs for most of these check engine light issues, the light may persistently stay on. Here’s are some tips to help you reset the check engine light.

Wait it Out

Some error codes such as a loose fuel cap will reset after repair if you drive for about 50-100 miles. As you drive along the system keeps performing certain tests. Once the criteria are met, it will turn the light off.

Disconnect the Battery

Disconnecting your battery for 10-15 minutes may clear the warning light. The disconnection discharges the control module memory consequently turning off the warning lights. Beware that this method may or may not work each time.

Have the Codes Cleared

After repair, a diagnostic tool like GOFAR will help you turn off the check engine light.

Not sure what the engine warning light is telling you? GOFAR provides a reliable and safe solution.

Install GOFAR in your car to receive plain English error codes on over 300 common issues with your car.

You can check whether your car is compliant or learn more about understanding your dashboard symbols and car warning lights on the spot.

Check Car Buy Now