Hi, recently i bought a honda civic v 1.6 esi (vtec), but it came with a really good question. When i put the key and roll it to start the car, the 'check engine' light won't turn off, and until it doesn't turn off, i can't start the car, like if i don't have battery. The weird thing is that it takes a long to turn off the light when the car it's cold, but when i use the car and it's warm, it's almost instantly to turn off the light and start the car..

Can someone explain to me what's the problem here?