l went ot Autozone for free code reading.
That is what l got:

Definition - H02S 12 Heater condition (heated Sensor Bank 1 Sensor 2)
Explanation - The PCM monitors the oxygen sensor heater. The computer has recognized a failure in this circuit.
Probable Causes - 1. O2 sensor defective. 2. Poor connection at oxygen sensor. 3. Check circuit - fuse.



OK, so should l go to a mechanic for an estimate? Should l do it myself and if yes, what is exactly the problem and what parts do l need?
Or just let it go? What does this problem mean to me? Will l get a lower fuel economy or something or can it lead to something serious?
Any help will be greatly appreciated.

look u go buy the o2 sensors and then take them to a mechanic they should charge less then 60.00 dollars to put them on but dont just put 1 replace them all there should be 4 hope these helps u

Buy an oxygen sensor,insist on Denso or Motorcraft made,(right side rear).Jack the car up,support it properly,use a 7/8 wrench and remove it (passenger side,rearward of catalytic converter).After done,remove 1 battery terminal for 10 seconds then reinstall it.Cost you somewhere around 60 bucks for part.HTH.

carmen is right on placement (passenger rear).. but will tell you that on the LS it is not really a easy vehicle to install o2 sensors on.

Recommend Motorcraft or Bosch (as Bosch actually makes the ones for Ford on that one if l remember)

The code basically means that a heater that is built in to the sensor to warm it up to work faster went out usually.

These are all good but your wrench wo not fit the O2 sensor it has to be bent at certain angle to get down on the nut , Take a Look at it and see what you think, l just changed mine on an F150 If the wrench was not bent at an angle l would have gotten them off, hope this helps.