Ford Repair: engine light on, tensioner pulley, oxygen sensors

Question
I have a 99 Ford Ranger extended cab, auto transmission, 3.0. The check engine light is steady.  All of the oxygen sensors have been changed and it's still coming on.  I've filled up the gas tank several times and this has also not helped.  The tensioner pulley squeaks, the belt has been changed but it still squeels. The idoler pulley squeels and the belt was changed too.

Any ideas what do try next?


Answer
Hello and thanks for the question...I'll try to help.
Before you go replacing parts in hopes of a fix.........have the computer system scanned for fault codes and make the needed repairs.
As for the belt......remove it and check ALL of the pulleys. If you can feel them you can diagnose and repair it better.
Erik