Anytime that your check engine light is on it means that a sensor did not pass the test that was conducted by the computer. If your check engine light is on and flashing then it means you have a catalyst damaging misfire. This means that your engine has a misfire and it can cause engine damage if not taken care of. This could be due to spark plugs, coil boots, or spark plug wires or ignition coils. We would have to test your components to know which as failed causing the issue.
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