Hello,
Im new to this board and hope to find a little help?...
Have a 2001 Montero XLS which has just thrown codes P0125 and P0170. Ive had a few temp related fluxuations in the gauges also and have read a little bit but not alot to maybe trace the causes and or problems.
Thank you

 

P0125 - Insufficient coolant temperature for closed loop fuel control
No idea what P0170 is. Are you sure that is the code?

P0125 is related to the engine temp. Computer has to feed different richness fuel mixture, depending on the engine temperature. You can try to replace the engine temperature sensor. It is pretty inexpensive and you can do it yourself (easy access and easy to do). Then clear the code and if you are lucky, that will be it. However, since you are getting multiple codes, you may have a problem with the O2 sensors as well. Work in steps - replacing the temp sensor will get you on on the right track. Good luck.