2001 chevy silverado problem?

My engine light came on 2 days ago. I checked my gas cap and it's on correctly. The truck has 78000 mi. I always keep the service up to date as best I can. I just dont have the money right now to have someone look at it. Would it harm the engine
if I waited 20 days for a mechanic to check it out. Please help !! (

Take your truck to Auto Zone for a quick and free diagnostic. Usually when the check engine turns on it for an emissions related problem. Check it ASAP or something else could and probly will go bad.