ok, logically this seems obvious but I'll ask it anyways. if I know for a FACT that coolant is mixing in the rotors(I change the oil & it's there) and am getting poor gas milage that means the o2 sensor is broken right? Now if I were to change the O2 would it go bad too? Can O2 sensors "go bad" if the motors on the way out?

 

The ECU only polls the O2 sensor when you are cruising at a steady speed and the throttle position stays the same for 3 or 4 seconds. The ECU will sample the exhaust through the O2 sensor to set up a more fuel efficient air/fuel ratio.

As far as changing the O2 sensor with a know engine problem, read this Q&A from Bosch web site about O2 sensors.


Q. What will damage my oxygen sensor?

A. An oxygen sensor can fail prematurely if it becomes contaminated with phosphorus from excessive oil consumption, silicone from internal coolant leaks, using silicone sealant in the engine, and some over-the-counter fuel additives. Even a small amount of poorly refined gasoline can kill an oxygen sensor. Environmental factors such as road splash, salt, oil, and dirt can also cause a sensor to fail, as can thermal shock, mechanical stress, or mishandling. However as required by vehicle manufacturers, Bosch sensors are designed and tested with these extremes in mind.

 

Project 84 thanks. I did do a search(gas milage) & read this somewhere but I didn't know of the Bosch report. Prior to me posting this I did a search & some have reported back with no improvement in their milage even when it's changed out. I didn't come across any positives(which I wish people would do). Also, someone had used a Chrysler O2 sensor since there is only one wire or something. I'll go with that info and think about it. Thank you again.