I have read all relevant post related to the o2 sensor, check engine light, vsc off, and vsc. My problem started yesterday night while driving home and my check engine light, vsc off, and vsc light lite up. I had the guys at autozone scan it for me to see the code p0051 af sensor heater control circuit low 21 and the probable cause is an open or short circuit condition, af sensor heater relay fault, and failed af ratio sensor. Do you guys think the O2 sensor need to be replaced or this is related to the fan that cools the o2 sensor? How much do you guys think this will cost me at Toyota because this is where I have always had my 2004 Sc430 serviced with 54000 miles? Any response will be appreciated.