When should you consider replacing the factory 02 sensors for a 2009 base Fit? I'm at 219,000 mi. New Ruthenium plugs were done at 175,000 along with all 4 coils (1 died). It would seem the 02 sensors would also be subject to wear and deterioration just like plugs and should be changed at some point, even if they are still working, but they may not be as efficient as they should be. Other than paying a small fortune for the OEM sensors from the dealer, what brands are reliable replacements?

 

Why replace something that works?

I would avoid Bosch as I had bad experience in the past with them. Would go Denso or NGK, nothing else.

 

They are currently working, no CEL or drivability issues, but with 216,000 mi. I am seeing poor fuel mileage, 28-29 highway @ 70 mph. If I run a bottle of Gumout Regane through 1 tank of gas, it immediately goes up to 35-37. Something gets cleaned, and it appears beneficial if done every 2-3 months

 

This is just my 2 cents worth. I would personally only run the same brand plugs in the car as were installed from the factory. How efficient are other brand plugs? You didn't mention if you have adjusted the valves when you did the plugs and coils. The valve adjustment is very important for fuel economy if done correctly. I would go back and do those things first and see if that doesn't improve your mpg. If you don't have an oxygen sensor related trouble code flashing, I personally wouldn't replace the oxygen sensors because they possibly may not be as efficient as when the car was new. If you choose to replace the oxygen sensor(s) (there are two), anyway, I personally would only use the oem/ factory brand sensors that can be purchased on the internet at a better price than the dealer. Good luck.

 

My mpg shot up when I got a new battery! If your voltage is minimal, the car will run fine until the battery fails. Just my experience. Clay