Pulling codes 172(lean) & 173(rich) on 95 ATX.. how can this be and what should I do?

[ACV1081]

I was recently helping out a buddy pull codes off his 95 ATX I sold to him a few months back and to my astonishment we are pulling both (in stored memory) a 172 and a 173 which indicate the HEGO sensors detecting both a lean and rich condition... so what gives? How can the car be running both lean and rich? O2 sensor/(s) or a deeper rooted problem? Car is getting terrible gas mileage and CE light is not constant. Any suggestions or ways to nail down the cause? Please help asap. TIA thumb

 

[wood_e]

Hey Adam!

I think he needs to get new O2 sensors. Obviously they are not reading corrently, or they don't read as effectivley as before. I got a 172 on my ATX coming back from minneapolis, but my gas mileage is around 27mpg...

I would replace the O2s, reset the computer and see if the codes come back pizza

<small>[ September 04, 2003, 06:04 PM: Message edited by: wood_e ]</small>

 

[sdpatt]

The rear bank O2 sensor is not switching and has read, in the past, both rich and lean. This is most likely an O2 sensor problem and depending upon age (if > 60K miles old), both sensors should be replaced.

172 (R,M) Oxygen sensor not switching - system is or was lean - Single, Right or Rear HO2S - Fuel control

173 (R,M) Oxygen sensor not switching - system is or was rich - Single, Right or Rear HO2S - Fuel control

 

[ACV1081]

Thank you both... I'll have him replace both O2s since we don't know much history on the car. I haven't had any problems lately myself so I have missed getting replies in these forums doh now I'll jinx myself probably