I wanted to know if there was a common failure point on the wiring harness for what I think is the rear O2 sensor? Is there a somewhat simple fix if there is a common one. It looks like the three DTC's all point toward the wiring so I figure I would start there. Thanks for any help.

My daughters 2007 Chevrolet Cobalt LT with the 2.2 L 4-cylinder engine (Current mileage: 93153) has the following DTC's:

From my Actron PocketScan Plus CP9550 scanner
P0036 (CNF) O2 Sensor Heater Control Bank 1
P0036 (PND) O2 Sensor Heater Control Bank 1
P0054 (CNF) Heated O2 Sensor Heater Resistance Bank 1 Sensor 2
P0054 (PND) Heated O2 Sensor Heater Resistance Bank 1 Sensor 2
P0141 (CNF) O2 Sensor Heater Circuit Bank Sensor 2
P0141 (PND) O2 Sensor Heater Circuit Bank Sensor 2

and from my
Vgate Maxi-Scan ECU-Provs890 scanner set to Chevrolet
$07EA
$07E8

I looked up online and found these explainations:

Potential causes of a P0036 trouble code may include:

Open circuit inside oxygen sensor or open power or ground wires to oxygen sensor
Exhaust system ground strap may have become corroded or broken
PCM/ECM or oxygen sensor heater circuit wiring has failed
Read more at: https://www.obd-codes.com/p0036


Potential causes of a P0054 trouble code may include:

Burnt, broken, or disconnected wiring and/or connectors
A faulty O2 sensor
Blown fuse or burnt fusible link
Defective engine control relay
Read more at: https://www.obd-codes.com/p0054


A code P0141 may mean that one or more of the following has happened:
An open or short to ground in the wiring harness
O2 heater circuit wiring high resistance
O2 heater element resistance is high
Internal short or open in the heater element
Note: Typically a failed catalytic converter does not cause this code. You're more likely to see a P0420 code for a failed converter.
Read more at: https://www.obd-codes.com/p0141

 

Make sure the wires are secured, I've had the wire for the rear O2 sensor come loose and drag. The wires eventually shorted and blew the underhood EXH / emissions fuse, giving me a bunch of codes related to both the O2 sensors and the MAF sensor. Inspect all the O2 sensor connectors and wiring harnesses for fraying, abrasion or signs of melting.

 

Just a followup. I had to have the sensor replaced . He said it was so difficult to get out that the threads needed to be chased to get the new one in. Cost me $130 with the sensor being a GM part.