After I drive my car for 45 minutes to an hour the oxygen sensors fail and I believe this to cause the car to misfire and run terribly. they are both reading 0 volts after a while of driving but function normally until then. A friend of mine has a 57 chevy and he put an o2 sensor on it to adjust the carb how he wanted it and said when he was running rich and it was hot his sensors would go to 0 volts as well. What could be the cause of this and what could be done to fix it?