Just a heads-up for a possible solution to a check engine light. CEL was on, and codes said it was possible cat converter and a few other things. There were two codes showing. The guy at Autozone who read the codes (for free) gave me a few things it might be. One of them was a dirty Mass Air Flow Sensor. Sprayed a can of MAF cleaner (removed it from engine first) and the CEL wen off and has been off for several weeks now. It was an $8.00 fix.
I hope this helps someone out there. (2001 Chevy Silverado, 5.3 V-8, 235,000 miles)