Service Engine Soon Light can't check codes
 

Hi all, a couple of months ago my service engine light came on in my 1997 Saturn SL1. It went off the next time I drove it so I thought it was not a big deal. I had a guy at O'reilly's look for the codes but he said there was an engine computer problem so the codes can't be read. The light came on and off a few times after that. I told my mechanic about it when they did the oil change and I figure he just reset the codes. Tonight the service engine soon light came on after I had driven 25 miles to the electrician union. When I drove back home it was on the entire time. I am having a mechanic take a look in a week or two. Is this a serious problem or something I shouldn't be too worried about? I checked the air filter and it looked kind of dirty my vehicle has 125,000 miles on it.

Thanks for the help!

With a few exceptions, when reading codes with a vanilla code reader, the Service Engine Soon light must be on to read the codes.

That being said, it is possible that

• the O'reilly's dude did not have the car already in "run" (key position) before attaching the reader
• the fuse for the circuit that includes the diagnostic port is blown and the port is receiving no power.
• his scanner was misconfigured and was trying to communicate in a protocol that your vehicle does not understand. Most code readers automatically try the different flavors of communications protocols until they find the one that matches, but with many, it is also possible to set it for one protocol and then forget to put it back in auto-detect mode.

Unable to connect messages can be triggered by multiple things.
If the dude couldn't get ANY response whatsoever out of his code reader Nothing on screen), it is probably a fuse issue.