Ok, i just replaced both o2 sensors, and the cat. I went with Bosch universal sensors, because of the price. I passed emissions, then a few days later a cel came on, its the o2 sensor heater problem code. What does this mean, is the o2 sensor defective, or is it an ecu problem. Please give me some ideas.

 

Oh yea, and it goes on and off, it came on a while back, then went away for a month. And it came back on today.