I have a friend with a 2002 Jeep Liberty with the 3.7. It had a check engine light on, I scanned it and found two codes-141, 161. These are the lower right and left bank O2 sensor, so I replaced them for him and 4 days later the light comes back on, so I scan the computer and there are codes 141, 161

Any idea's, I am kind of lost, I think it is unlikely that both sensors died again at the same time. These were Chrysler Bosch sensors, not some el-cheapo piece of junk.

Thanks

 

The 141 is the O2 sensor heater failure on cylinder bank 1, sensor 2. 161 is the same thing, but for cylinder bank 2.

If the sensor heater circuit is failing, have the rig scanned with DC-Jeep's proprietary scanner. There will be companion codes that are telling you that the idle circuit or cold start circuit on the fuel injection is running way too rich, or the ECM is failing.