the engine light on my blazer is on, i took it to autozone and they pulled the code, it came up with "small emissions leak" or something like that. the code was P0455. They guy said more than likely it was the gas cap so i replaced it. the light went away for a couple but has come back on and has been on for the past month or so. I was wondering if a leak in the exhaust system would cause the engine light to come on. thanks for any help. my blazer a 2003 4x4

 

Nope, this is a leak in the EVAP system.

If you have already replaced the gas cap and made sure that it was properly tightened (3 clicks) then it is possible that it is caused by a leaking vent solenoid.