P0161 code


I got the P0161 code on my 96 Sable with the Duratech engine(dual OHC).

The code description is HO2S 22 heater condition. There is a failure in the heater circit of the O2 sensor, bank 2 sensor 2.

Before I spend the $60 plus on a new O2 sensor is it likely the issue is in the wiring circit else where? When I reset the code it seems to take a day or two before the check eng. light comes back on.

I know many times people here have posted that statically testing an O2 sensor is not often reliable.

Anyone experienced with the idiocyncrities with this particular make and modle?


Yes, you can test an O2 statically.

Unplug the O2 connector and with the key ON, verify that power is provided through the red wire terminal. This red wire goes to all of the O2s (and numerous other items) and most likely you do have power here.

That means either the O2 has a bad circuit internally (likely) or has a bad ground in the ECM (not so likely).
Each O2 is provided its own ground by the ECM.
The ground wire color varies with each O2 but a digital VOM can be used to test continuity through the heater circuit.

A digital VOM can be used to test the heater circuit and the O2 output when the engine is running, but must NOT be used to test resistance through the O2 output circuit.

Hope that helps.


Check the WIRING resistance with the digital multimeter. When the engine is running, the VOLTAGE output of the oxygen sensor should constantly vary between 0.1 and 0.9 volts. A good average is 0.450 volts. To check the heater, the circuit should be about 12 volts dc.