My daughter purchased a 2005 Jeep Liberty and loves it. About a month ago she recevied an O2 sensor (P0038) code. I replaced the sensor and all was good until a few days ago. The same error code is back. I replaced the O2 sensor again but this time it will not clear. I checked the connector at the O2 sensor and I am not getting 12 volts to the heater circuit. Is there a fuse or relay that feeds the O2 sensor? If so which one is it?