When the Check Engine light is flashing, that indicates the most severe type of problem and you're supposed to stop the engine as quickly as safely possible to avoid an expensive failure of the catalytic converter.
The least severe defects do not adversely affect emissions. The diagnostic fault codes for those problems do not turn on the Check Engine light.
For the more minor problems that could affect emissions, the Check Engine light will turn on while the problem is occurring, then, if it's an intermittent problem, the light will turn off while you're driving if the problem stops acting up.
For more severe intermittent problems, even if the defect stops acting up, the Check Engine light will remain "latched" on until the ignition switch is turned off, and the engine is restarted. At that time the light will stay off until the problem occurs again.
For the next level of severity, even if the problem clears up momentarily, or hasn't acted up during multiple drive cycles, the Check Engine light will be on anytime the engine is running. The light will only turn off if the diagnostic fault code is erased.
The highest level of severity is almost as serious as the "Oil" pressure warning light. This is when it's flashing. That means too much unburned gas is going into the exhaust system where it is going to burn in the catalytic converter causing the catalyst to melt and block the exhaust gas flow. That can turn into a very expensive repair. The most common cause of this problem is a spark-related misfire.
The place to start is by having the diagnostic fault codes read and recorded. Those indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. Be aware those fault codes never say to replace a part or that one is bad. They only tell us where to start with the diagnosis. When a part is referenced in a fault code, it is actually the cause of that code only about half of the time. First we have to rule out wiring and connector terminal problems, and mechanical problems associated with that part.
The people at most auto parts stores will read those fault codes for you for free. Once you know the exact code number(s), you can go here:
https://www.2carpros.com/trouble_codes/obd2/p0300
to see the definitions, or I can interpret them for you. You will find more dandy information in this article:
https://www.2carpros.com/articles/what-is-a-check-engine-light
Let me know what comes up for those diagnostic fault codes.
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Monday, March 6th, 2023 AT 12:48 PM
