Warning Light

[hottest_cc2]

My diagnostic light has been on for around 3 weeks now, took it to pug the day after it came on and they said there wasn't any problems, just a fuse had blown. So that was fine. But the next morning it came on again, took it back to them and they ran it on the machine again and it came back with no errors? But everytime they have it the light goes off for a few hours and then comes back on but when they check it no errors are coming up still.

Help needed please!