I have a test pipe on my Evo with the O2 CEL fix. Recently I started popping my engine control, or whatever, fuses and realized it was due to my O2 sensors wires banging againt the chassis and shorting....

Long story short, one of the ground wires on the O2 sensor got completely chewed through so the sensor is no longer reading. Are there any driveability issues related to the O2 sensor not reading? Or is it just a smog issue?

This is just a curiousity question cause I ordered a new O2 sensor today.

Thanks in advance for any advice on this.

 

Shouldn't have a problem with a bad rear o2. With a bad front o2 you would get terrible mileage because the front o2 is what's the ECU uses to control fuel.

 

Awesome! Thank you so much!

 

there is a patch in the ecuflash sub-forum to disable the rear o2 sensor all together

 

Closed loop (computer is using the front O2 sensor) occurs when you are driving at a steady speed. Punch the gas and you fall out of closed loop. So, I'd suggest much of intown driving is not closed loop.

My DSM with a failed front sensor (there was no rear sensor) had improved driveability. I didn't check the gas mileage.

 

I literally just had my front o2 sensor changed at the dealer (under warranty). For about 4 months up until it finally went bad, I was regularly getting 320-340 miles per tank. Now that its been repaired, I'm getting around 300 miles so it leads me to believe that as it was getting worse, it was sending a "rich" reading, thus the ECU compensated by leaning it out.....but I could be wrong. I haven't changed driving habits at all either....

 

On my DSM I did the full test - power to the heater and a meter across the sensor, engine on and goosing it - just like the service manual says. There was very little signal. Once I had the new sensor installed I did the same test and obtained a sharp signal.

There may be other ways an O2 sensor fails but if it fails like mine did then you would be in open loop all of the time.