A few nights ago I was driving when my check engine light came on. I got a code reader and the codes thrown ended up being P0300 & P0301.

I did some research, tried a few things to fix the problem, and then cleared the codes via my reader.

Ever since I've done that, my check engine light no longer comes on, but my reader is still showing those codes being thrown.

Why is that?

Thanks.

 

bump

 

Could still be a problem. If there is a malfunction in a monitored circuit unless certain criteria are met a fault code won't be entered into the computer memory so the CEL won't be lit. I ran into this when I was having IAC and CTS issues. Codes but no CEL.

 

What did you do to fix the issue? Those codes are for multiple misfire and misfire on cylinder 1. When the light came on, was it blinking then stayed on or did it just come on steady?

 

It came on and stayed on.

All I did to fix was play with the plug wires and make sure they had a good connection. I doubt that fixed it, and I'm currently trying other things. I'm just confused as to why it threw a CEL the first time but never since, even though the same codes are seemingly showing up on the reader.

 

I mean if it's fixed as you say you may unplugged the battery and clear the codes that way. Run it for a little and if the light doesn't come back on then see if the codes are still there.