If you have a flashing check engine light and a car shaking from the engine, you can test for an engine misfire with these tips. You’ll find out what to do if this happens, how to test the engine yourself with a spark tester, and why it’s important not to ignore this issue.
How to Diagnose and Fix a Check Engine Light Flashing and Car Shaking
Steps to diagnose and fix a check engine light flashing and car shaking
- Check the OBD-II System for a Diagnostic Trouble Code (DTC)
The OBD-II system in your car may have stored a DTC for an engine misfire. Check for an engine misfire code with a scan tool if the check engine light is flashing and the engine is making your car shake. This can help you find which ignition coil is causing a misfire.
The number at the end of the code indicates which cylinder is misfiring. For example, code P0303 indicates a problem with cylinder 3.
More on engine misfires and diagnosing them
- Test the Ignition Coil and Spark Plug with a Spark Tester
You can test the ignition coils and spark plugs with a spark tester. You’ll connect the spark tester to the ignition coil and spark plug. When you start the engine, if the light turns on, there’s spark. If there’s no light, you’ll know where the misfire is.
How to test an ignition coil without a spark tester
- Replace the Ignition Coils and Spark Plugs
Once you’ve found the defective ignition coil or spark plug, replace it with a new one. We recommend replacing the spark plug and ignition coil together. We also recommend replacing all of the ignition coils and spark plugs at the same time.
Replacing ignition coils on V8 and 4-cylinder engines is generally an easy repair. On most of these engines you can easily access the ignition coils. Replacing ignition coils on a V6 engine is generally harder and may require removing an intake manifold. We recommend replacing the old intake manifold gasket with a new one before the intake manifold is reinstalled.
Typical Steps to Replace an Ignition Coil and Spark Plug
– Spark plug socket
– Socket, socket extensions, and ratchet
1. Disconnect the electrical connector from the ignition coil
2. Remove the bolt from the ignition coil
3. Pull the ignition coil up and out
4. Loosen the spark plug with a spark plug socket, remove the ratchet from the socket, and remove the spark plug by hand
5. Install the new spark plug into the socket, insert the plug by hand a few threads and torque it to manufacturer specification, being careful not to overtighten
6. Install the ignition coil
7. Tighten the bolt to the ignition coil
8. Connect the electrical connector to the ignition coil
Why You Want to Fix an Engine Misfire That’s Causing a Flashing Check Engine Light and a Shaking Car
Unburnt Fuel Can Damage Parts Like the Catalytic Convertor
If your car is shaking and your check engine light is flashing from an engine misfire, you’ll want to fix this problem as soon as possible. Ignoring this problem can cause the unburnt fuel in the engine to collect in and damage parts like the catalytic convertor. Fuel can collect inside the convertor and cause it to overheat, clog, and damage the internal components over time.
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