check engine light on 2003 Chevrolet Express 2500

My check engine light would sometimes come on in the winter. This last winter it did not. Now it came on about a week ago. I went to autozone to have them pull the code and the instrument say it must be connected to vehicle. I'm trying to figure out why it won't read the code.

1 answer 2 comments
I would recommend a proper diagnosis be performed by a qualified technician, not a clueless parts store trying to sell you parts based off of a code pull...that they apparently aren't capable of doing.

It's possible you may have a blown data link fuse?

In any case, check engine lights can come on for many reasons, and only a true diagnosis can get to the bottom of the problem.
It wouldn't read because the fuse for the lighter was blown. Go figure. Anyhow it was a p0442 which is with the evaporative system. Thanks for tryiing
Yes, the lighter fuse is also what powers your data link. So - indeed so.

P0442 - yes, have your evap system diagnosed.