Had my o2 sensor replaced on my 2003 dodge Dourango 4.7 because it was getting lazy. It never set any codes. Now with new sensor, when vehicle gets cold it sets P0135. I went out and bought another sensor and it too sets the above mentioned code when cold. It is almost like the heater in the sensor is not working. Have tried to find how the sensor gets it's power but cannot find a fuse in the tray in the engine area. The fuse box has an area marked o2 sensor but it is empty as well as the o2 sensor relay is also empty. My question is how does the sensor get its power. This vehicle has only two sensors one upstream and one down. Any help would be greatly appreciated ! Thanks in advance!!!