Nissan Repair: check engine light, oxygen sensors, ford freestar

Question
I am working on an 04 Ford Freestar.  The check engine light came on, so I hooked up the computer to see what the problem was.  At first it was the o2 sensors, so I replaced all four to be safe.  Now I am getting a reading for heater resistance ?  The code is P0052, but I have NO idea what it is.  Can you tell me what it is, and how to resolve the problem ?

Answer
Steve,

The code P0052 is the heater circuit for the oxygen sensors.  Since it is not a specific call out for one of the oxygen sensors I would assume that you have either a broken wire to one of the new sensors, a bent over pin or the thermal relay that heats them is defective.  Most probably the thermal relay.  This is a timed relay that comes on when you start the vehicle and after a couple of minutes it turns off.  You see, the oxygen sensors self generate the signal that the engine's computer reads.  However, they are really lazy when the car first starts due to them being cold.  The timed relay that feeds power to them is only warming them up so the vehicle can come under the computer's control sooner.  Check it out and email me back if you need more.