A couple of weeks ago the check engine light came on. And I've been getting notifications telling me to tighten the gas cap. I that's what the problem was. I ordered a locking gas cap and I'll see if that helps.b
It runs great.
I posted the picture of my Tahoe as my avatar
tighten cap is code for "small vacuum leak" which as others have noted is a fuel evap issue
so.....the problem is, trying to diagnose this is tricky at best and basically it comes down to how do you want to gamble your money?
you can go to a mechanic and pay for a diagnostic $$$ + plus the part and labor, provided they can actually pin it down and not just take a guess, even then it may or may not fix the problem and you may or may not have to take it back a few days later and pay for another part.
or you can piece meal it out yourself and hope for the best at potentially lower cost.
or you can shot-gun it with a parts cannon and cross your fingers the problem says away for years again...
there are basically 3 parts to the system and if you buy all 3 parts OEM and DIY (not hard to do) it will run you about $250 or so if you shop around
that's diy option 1
or you can try 1 part at a time, starting with the cheapest easiest one and see how it plays out.
that 1st one being the under hood (purge valve solenoid), oem is about $25-35
*** sometimes, although rare a new gas cap may work, if you roll a 7
basically all you really can do is throw a parts/parts at it, clear the code and wait a few days to see if it returns or not it takes atleast 3 full drive cycles for the code to clear
in any case USE OEM parts for this, as aftermarket is prone to fail in short order.
you can drive it like that without causing any damage to anything it's just a smog device but if you have state inspection, smog check then that may prevent new registration until it is resolved.