Hi. I have an '01 S40 with the oh so popular po128 check engine code. I followed everyones advice and changed the coolant temp sensor AND thermostat. 2 days later, the check engine light is back on and the po128 code returned. Anyone have any ideas about my next step here? Thanks, in advance.

 

How fast did the code return?

Maybe the computer didn't respond fast enough to seeing the repair being done.

 

Within 2 days.

 

Did you try resetting again and see if they come back fast?