Nissan Repair: Nissan 2000 Pathfinder O2 Sensor, oxygen sensors, o2 sensors

Question
I replaced one of the O2 sensors on my Pathfinder which was defective (No heather).  The cables were too long and they short circuited.  The same O2 sensor was replaced and the related fuse (which blew) also.  Now I get four fail codes in the ECM, one for each sensor and all related to the heather element of them.  I checked the sensor individually and they are OK.  There is no current going to the sensors heathers.  Could it be that the ECM is damaged?  What do you recommend?

Answer
Rodolfo,

Yes, the ECM could be damaged but there is a timed relay that grounds the heater circuit for a given period of time to get them working fast.  Remember that oxygen sensors are self generating and they do not work well unless they are at operating temperature so the heater gets the unit working faster so the engine can go into open loop to control the fuel.  I would look at where the sensors hook together for heat and they work for a short period of time to heat them up and then turns off when the sensors get to temperature.