Check Engine Light 2003 S60
 

Light has been on for a few weeks but the car drives just fine. No hesitation or problems idling. Checked gas cap and actually purchased a new one to make sure it would not be a problem. Disconnected the battery and the light went off for the first restart. Next restart it was back on and stayed on. Any ideas what the cause could be?

How about getting the codes read.

Thanks for the suggestion. That is what I did and received the following code:

P0037 - Heated Oxygen Sensor Control Circuit Low.

From my discussion with the sale person at Advance Auto there seem to be two possible sensors it could be. One that is in front of the catalytic converter and one behind. Is that a correct diagnosis from him and if so how do I find out which one needs to be changed?