96 V8 Explorer AWD XLT. Check engine light on. Dealer says it is the Egr and RH 02 Sensor. I looked there are four sensors. Which is the RH? Also Check sensors to buy, they say before cat and after cat from what i can tell right before cat conv and both after cat are the same and the left one is different. Anyone know for sure?

 

Do you know the code from the computer? Should be a letter followed by 4 numbers. This should give you more detail than just right hand O2. It should tell you sensor 1 or 2.