Well I just spent $200 and have changed the 02 sensor in my 535I 89. That bastard of light is still on and still gives the same erro code (1264 02 sensor heater). I havn't noticed any difference at all on the car. It still drinks heaps of fuel and idles rough. What the hell is going on? In the relay box near the strut tower how many relays are there supposed to be? Mine has 3 and space for 2 more! Anyone know how to get that friggin light reset?