Clio 172 rear o2 sensor HELP :(

[Jonnycressey]

I bought a clio 172 to end my tuner car bad luck...
2 days into owning it! Its started occasionally missfiring/ holding back. And usin LOTS of fuel! I had the car plugged in and cleared all the old codes so that there wouldnt be any confusion. We noticed that the rear o2 sensor was just flat lining..... So i have ordered a new one, but does the second sensor actually affect the cars running or not? Ill cancel my order if not . CARS

 

[MicKPM]

The rear is supposed to give a constant value IF the CAT is working right.

 

[MartinR]

As Mick said above the rear sensor sits near enough on a constant value and the front one fluctuates.

Swap them round .

 

[MikeClio172SPT]

The rear is supposed to give a constant value IF the CAT is working right.

this is correct

Id look at the live data to see if your getting a constant voltage.

 

[MicKPM]

It will fluctuate if you're gonna be live data logging from cold start but once the CAT is up to temp the voltage should be stable both at idle and when under load.