Check engine light off after check codes

my truck spit out a check engine light so i went to go have it read.

after reading code, i started my truck again and the light doesn't come on any more.

i think the code got erased but the tech at the auto parts store said he wasn't going to clear it, so if he did it was an accident. although i not sure if computer will let you clear it unless you disconnect battery for a while or fix the problem.

i figure if it wasn't just a random mishap (since truck runs fine) it will come back on. is that a safe assumption or not?

code was (P0115) engine coolant temperature sensor if that matters any.

 

The guy probable cleared the code. If the coolant temp sensor is bad the check engine light will reappear.

 

what i was thinking as well.

 

Yes it can happen. Check for a code, read it, and just disconnect and it clears. Have no idea why... Could be a glitch in the software of the scan tool.
My hand held has done it a couple on times in the past few years. If it happens again and it's the same code then get it looked at.....