I just bought a 99 xj with 3 codes.
p118 engine coolant sensor circuit high input
p132 sensor circuit high voltage bank 1 sensor
p138 sensor circuit high voltage bank 1 sensor2
is there any way that replacing the coolant sensor would eliminate the other o2 sensor codes? Or should I just go ahead and do all 3 at one time? Thanks for help!

 

I would think that they're all separate. but it cant hurt to replace one at a time and see if it turns the others off

 

The P118 will probably be resolved with a new coolant temp sensor. Be sure to inspect and clean the sensor connector (any engine management sensor connector for that matter) with a spray of electrical contact cleaner which is available anywhere. A can of that should be in your garage.

The other two pertain to an upstream AND a downstream oxygen sensor circuit.

If the sensors have between 100k and 150k on them, replacing them would not be a bad idea. These sensors DO have a finite lifespan!

But before you do that, there is a fuse for the oxygen sensor circuit. It is located inside of the power distribution center (black box) under the hood. It might not be identified on the cover of the box, but it is around slot 16-17, check all fuses just to be sure.

And if you go with new oxygen sensors, search out a name brand like Bosch or NTK. Stay away from no-name e-bay sensors. They are junk.