I'm getting a code P 0139 02 circuit slow, bank 1 sensor 2

what is it ? I scan the truck because for no real reason, all of the sudden the engine start to get hot after a 5 minutes ride (didn't go to the red) and then went back to normal temp. it did it twice.

forgot, disco II 2001 98K miles

 

P0139 Oxygen Sensor Slow Response *Codes* A D
http://www.troublecodes.net/landrvr/

 

At your mileage, you should replace all 4 02 sensors. That being said, this is not causing your overheat issues and this needs to be addressed ASAP. Have you been having to add coolant lately, or smell it?

 

no, I haven't , I check the coolant a week ago and it was fine. should I just remove the old coolant and put new one ?

 

Read your owners manual, LR recommends replacing the coolant EVERY 45,000 miles or 36 months, whichever is sooner.