2G P0170 Code, fuel trim?

[brian102]

Im throwing this code it has straight exhaust the whole way back. No cat converter. This was donr by previous owner on my scanner at idle the rear 02 sensor shows .8 volts not aure what a rear should run. Im getting horrible gas mileage. Thanks

 

[turboJAKE]

your rear o2 is for emissions nothing more. if you are having bad gas mileage look at the front o2

 

[ECLIPSEESPILCE]

.8 on the rear o2 is indicating rich. Does the voltage change if you create a vacuum leak? Monitor rear O2 voltage and pull a vacuum line off creating a vacuum leak. If the voltage drops under .45, hopefully to .10 or lower the o2 is functioning. If there is no change the o2 may be at fault or the vehicle is actually rich. If there is no cat the front oxygen sensor should mirror the rear sensor readings.