Check Engine Light - Questions & Answers

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Question: I had my car scanned for the check engine light being on and blinking. i was told it was the egr valve. i purchased it and had it installed.. the light was out for about an hour but came back on and started blinking and the bad idling i was having is also back. i contacted auto zone who told me this was the problem and the man who did the scan said i have to get someone to turn the check engine light out or it will continue to do that. and that this is also what is causing it to idle poorly. is this true and who can one get to turn this light out? Sharon, August 2008.

Answer: Hi Sharon, thanks for the question. When the Check Engine Light comes on, it stores a trouble code in the car's computer memory. I'm guessing your trouble code was P0401 Exhaust Gas Recirculation Flow Insufficient Detected, which is a very common EGR code. It could also be a few similar codes (P0400, P0402, P0403). Feel free to search the Internet on any of those codes for more specific information.

Although the code refers to the EGR system, it doesn't necesarily mean that the EGR valve is the problem. The folks who work at the parts stores don't always interpret the code properly... Keep in mind their job is to sell you parts, not fully diagnose the problem. You may want to go back and get the actual code (like P0401 for example), do a quick Internet search and you'll probably find a lot more information specific to your issue.

Anyway, here are some typical things to check - manually verify the EGR valve operation using a vacuum pump; if equipped, check your DPFE sensor (differential pressure feedback).

To answer your question though, the act of clearing the trouble code will not fix the problem. Once you've taken some corrective action such as replacing a part, you need to clear the code. If it returns then you need to diagnose further. So no, simply clearing the code will not fix anything at all. The car still has symptoms so it still needs some sort of attention. If in any doubt as to your ability, please contact a trusted, qualified technician. Thanks for the question.


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