2010 Mercedes-Benz GL350 3.0L with code P20BE, O2 sensor replaced 10,000 miles ago

Question

I find 1 upstreem O2 sensor Part# 0065421718 and 1 precat Nox sensor part# 0065420918 and one Nox sensor after the Cat sensor part#0065420918.
Are these all that are on this Car.
2010 MB GL350 Blutec.
Upstream O2 was replaces at 58k now at 68k 6 months latter and getting this error code from the OBD2 reader Torque P20BE
P20BE Heating of component G3/4 (Right O2 sensor,before TWC[KAT]),Voltage supply (P0135)

P20BE component G3/9 (right O2 sensor,before CAT,cylinder 1-3) heating,supply voltage (P0135)
P20BE Heating of component G3/4 (Right O2 sensor,before TWC[KAT]),Voltage supply (P0135)

Answer 1

Start by checking the Adblue Tank Heater wiring and connection, if the connection is OK, then the Adblue Tank Heater is the most likely cause of the problem.

P20BE MERCEDES-BENZ - Reductant Heater 'B' Control Circuit Performance
Read more: https://www.autocodes.com/p20be_mercedes-benz.html