A flashing check engine light usually indicates a serious problem with your engine, such as a misfire, which is usually caused by various issues, such as faulty spark plugs, fuel injectors, or vacuum leaks.
But what does it mean when the check engine flashes after tune-up?
Your check engine light is flashing after a tune-up because you installed a defective or incompatible part or you have damaged or disconnected something during the process.
Check the connections and the condition of the parts you replaced or worked on during the tune-up. If you are unsure how to fix the problem, you should take your car to a professional mechanic as soon as possible.
In this blog post, I’ll explain why the check engine light flashes after a tune-up and how to fix it.
You might also be wondering about the differences between a flashing check engine light and a solid one, be sure to check out our article on flashing check light vs solid.
How Does Tune-up Impact the Check Engine Light?
A tune-up can impact the check engine light by positively affecting the overall health of the vehicle’s engine.
During a tune-up, components like spark plugs, ignition coils, and sensors are inspected and, if necessary, replaced or adjusted to ensure optimal engine performance.
When these components function correctly, it reduces the likelihood of issues like misfires or sensor malfunctions that typically trigger the check engine light.
Essentially, a well-executed tune-up helps maintain the engine’s efficiency and minimizes the chances of the check engine light coming on due to common performance-related problems.
Reasons for a Flashing Check Engine Light After a Tune-Up
Some possible reasons why your check engine light is flashing after a tune-up are:
1. You Have Installed a Faulty or Incompatible Spark Plug
Spark plugs are responsible for igniting the air-fuel mixture in the engine cylinders.
If they are defective or not suitable for your car model, they can cause a misfire, which means that the combustion process is incomplete or uneven.
This can result in poor engine performance, increased emissions, and damage to the catalytic converter.
2. The Ignition You Installed Is Faulty or Incompatible
Ignition coils are responsible for generating the high voltage needed to create the spark in the spark plugs.
If they are defective or not suitable for your car model, they can also cause a misfire, as well as other electrical problems.
3. Due to Faulty or Incompatible Fuel Injectors
Fuel injectors are responsible for delivering the right amount of fuel to the engine cylinders.
If they are defective or unsuitable for your car model, they can cause a lean or rich fuel mixture, which means that there is either too little or too much fuel in relation to the air.
This can also result in a misfire, as well as increased emissions, reduced fuel economy, and damage to the oxygen sensors and the catalytic converter.
4. You Have Damaged or Disconnected an Oxygen Sensor
Oxygen sensors are responsible for measuring the amount of oxygen in the exhaust gases.
They help the engine computer adjust the fuel injection and ignition timing to optimize the combustion process and reduce emissions.
If they are damaged or disconnected, they can send incorrect signals to the engine computer, which can cause a misfire, increased emissions, reduced fuel economy, and damage to the catalytic converter.
5. You Have Created or Worsened a Vacuum Leak
Vacuum leaks are caused by cracks or holes in the hoses, gaskets, or other components that connect the intake manifold to the engine and other parts.
They allow unmetered air to enter the engine, which can disrupt the air-fuel ratio and cause a lean fuel mixture.
This can also result in a misfire, increased emissions, reduced fuel economy, and damage to the oxygen sensors and the catalytic converter.
How to Fix Check Engine Light Flashing after Tune-Up
To fix a check engine light flashing after a tune-up, you need to follow these steps:
1. Scan the Car Computer for the Stored Fault Codes
The best way to diagnose the problem is to use an OBD2 scanner to read the trouble codes set in the computer. You can use a variety of OBD2 scanners to figure out what’s going on, but some read more codes than others.
The trouble codes will tell you which system or component is malfunctioning and help you narrow down the possible causes.
2. Check the Connections and the Condition of the Parts That You Have Replaced or Worked On during the Tune-up
Depending on what kind of tune-up you did, you may have installed new spark plugs, ignition coils, fuel injectors, oxygen sensors, or other parts.
You should make sure that they are compatible with your car model and that they are not defective or damaged.
You should also make sure that they are properly connected and secured and that you have not accidentally disconnected or damaged any other wires, hoses, or connectors during the process.
3. Replace or Repair the Faulty Part
Once you have identified the cause of the flashing check engine light, you need to fix it as soon as possible.
Depending on the severity of the problem, you may be able to do it yourself, or you may need to take your car to a professional mechanic.
Some common fixes include replacing a faulty spark plug, ignition coil, fuel injector, oxygen sensor, or catalytic converter, cleaning a dirty MAF sensor; sealing a vacuum leak, or tightening a loose gas cap.
4. Clear the Trouble Codes and Reset the Check Engine Light
After fixing the problem, you need to clear the trouble codes from the car computer and reset the check engine light.
You can do this by using an OBD2 scanner again or by disconnecting the battery for a few minutes.
However, be aware that disconnecting the battery may also erase some other settings and data from your car, such as radio presets, clocks, etc.
You should also drive your car for a while and make sure that the check engine light does not come back on.
Why is my check engine light blinking after changing spark plugs?
A blinking check engine light after changing spark plugs indicates a misfire in one or more engine cylinders.
Can I still drive my car if the engine light is flashing?
While it’s generally safe to drive the car for a very short distance, prolonged driving with a flashing check engine light can exacerbate the problem.
The potential reason for a flashing check engine light after a tune-up is misfires caused by damage to the vehicle’s components during a tune-up.
By addressing issues like misfiring spark plugs, faulty ignition coils, vacuum leaks, or other performance-related problems during a tune-up, you can significantly reduce the chances of encountering a flashing check engine light.
Regular vehicle maintenance and prompt attention to any warning signs can help ensure your car’s reliability and safety on the road.