Flashing Check Engine Light? (Here’s What to Do)

A flashing check engine light on your dashboard may lead to many questions. Read on to learn everything you need to know when this happens

flashing check engine light

You drive your car, and suddenly from nowhere, your check engine light starts flashing on your dashboard.

What to do now? Will my car get damaged if I keep driving it? How much will it cost? There could be a lot of questions that may be running through your head.

Luckily, we will cover everything you have to know about a flashing or blinking check engine light in this article. Let’s begin!

What Does A Flashing Check Engine Light Mean?

A flashing check engine light signals an emergency and requires immediate repair. The more you drive with a blinking check engine light, the more damage you may cause to your engine. It is often caused by a misfire due to fuel or spark problems.

The engine control unit monitors all sensors in your car while you are driving and with this information, it calculates how much fuel should be injected into the engine and at which angle it should fire the ignition.

If one of the values from a sensor is faulty for a short amount of time, it will trigger a trouble code. If the engine control unit is getting the wrong value from the sensor several times, the check engine light will appear on your dashboard.

If this problem is severe from a misfire, it will start to flash the check engine light instead. This is to notify you that a problem that may damage the catalytic converter is happening right now.

check engine light

Causes of a Flashing or Blinking Check Engine Light

  • Misfires on one or several cylinders (most common)
  • Faulty spark plugs/Coils
  • Faulty engine sensors (coolant, air temperature, exhaust temperature sensor, etc.)
  • Faulty EGR valve
  • Faulty/bad injectors
  • Faulty crankshaft/camshaft sensor
  • Exhaust emission problems
  • Boost/overcharging problems
  • Internal engine problem (rare)
  • EVAP trouble codes

A flashing or blinking check engine light is most often caused by misfires. However, it is not as simple as that because many different things can cause misfires.

RELATED: Will the Check Engine Light Reset Itself?

How to Diagnose a flashing check engine light?

mechanics diagnose car

So now, when we know what could cause this, where should we begin to pinpoint the problem?

You must understand that every time your check engine light is constantly lightened up or blinking, it will store a trouble code in the memory so you will have a chance to see what was causing the problem.

Therefore it is a terrible practice just to guess which parts could cause the check engine light and start to replace parts. This will, in almost all cases, just make you waste your money.

A much better and more efficient method is to check what the engine control unit is trying to tell us. This can be done with a diagnostic scanner.

You may think that a diagnostic scanner is too expensive for this small problem, and in that case, you can borrow one from a friend or just take your car to a repair shop and let them read the codes for you.

After you have received the engine control unit’s codes, you will most likely find a trouble code related to a misfire. Check for more related trouble codes to continue the troubleshooting on that trouble code.

For example, if you get a misfire trouble code and one related to an ignition coil, you should definitely continue the troubleshooting on that ignition coil.

If you get misfires on a specific cylinder – check the spark plugs, ignition coils, and wirings. If you get misfires on several cylinders, there is most likely an issue with a too lean or too rich mixture.

Written by:

Magnus is the owner and main author of MechanicBase. He has been working as a mechanic for over 10 years, and the majority of them specialized in advanced diagnostics and troubleshooting. He has also been a motorsport (drifting) driver for over 5 years.