DO NOT RECOMMEND THIS FOR A SMOG CHECK. I am a woman and know nothing about cars. My car is fairly new so when my check engine light came on I it was a surprise because there didnt seem to be anything going on with the car that I noticed. Anyway, I didnt know that the light would be cause for a FAIL on a smog test, its a light, this is a new car and we are checking for hazardous fumes right. So anyway, I saw smog guy check my gas cap right after getting in my car and I thought..."oh, he saw the light too and I heard that might fix it". I guess it didnt work because he ran the test (KNOWING IT WOULD FAIL AND NOT WARNING ME). Of course it failed, and then he said "Everything passed except that light is on so it's a fail". Thanks for charging me $40 to tell me the obvious and not warning me ahead of time. WHAT A SCAM!!!