So I have these 2 codes in my 2004 MCS, 71K kms, that I can clear with my Icarsoft i910 & Thinkdiag but shows back after I start the car for the past week now. I checked for leaks and there is none.
I also reset all Adaptation Values using my Thinkdiag to no avail. (Air Intake Pressure, Electronic Throttle Valve Control, Mixture adaptation, Knock Control, Lambda Emission Control, Ignition Timing).

Today, I ran a Live Data Stream using my iCarsoft and noticed that the post cat O2 sensor raw voltage value is constant at 0.11 volts at idle and revved engine. I believe the normal range is 0.6V-0.8V steady. I will replace the post cat O2 sensor with NTK brand and I hope that it will solve my problem. I have Mynes 4:1 headers with 200 cell cat & IE cat-back exhaust. The post cat sensor has O2 spacer bung since 2009 and have only encountered the P0420 that I can clear but not anymore together with P2096.
Could this also be a sign of failing Cat?

S O L V E D !

 

Update:
I thought there was no exhaust leak along the manifold Cat when I pressure tested with air and soapy water but when I started the car and tested it again, the V-band clamp that connects the headers to the cat converter was leaking air. I tightened the clamp, clear the code with my Thinkdiag. The CEL is still there after start-up but cleared away after driving for 15 minutes city drive.
Happy with the result as I thought the post cat O2 sensor was the fault, but not.


CEL cleared