Laddbg

Looking for some guidance on tuning an O2 sensor. I read the tech article https://www.audiworld.com/tech/eng53.shtml and installed the diode on bank one as instructed. With the diode wired in line the voltage reading back to the ecm is now .45 volts. The diode has eliminated the "Precatalyst efficiency below threshold" code. But know I have a new code that reads P0139 O2 Sensor Circuit Slow Response Bank 1 Sensor 2. So evidently my car looks at this sensor differently than what the tech article suggests. Did I cut the voltage to much? Any other methods to reduce voltage slightly to get rid of this engine light?
Any and all help appreciated.

Thanks,
Bryon