Hi All and a Happy New Year.

Could you guys please advice , maybe someone had the same issue .

About 8 months ago I had an engine light on the dash and after I scanned it with my Xentry 2020 I fount the fault below:

• P220F77 - The heater of NOx sensor 2 (cylinder bank 1) has an electrical fault. The commanded
  position cannot be reached.

I managed the find one online ( removed from damaged car ) and I have replace it ( it was the last Nox sensor looking from the engine side ) plus I did reset the all values...and removed the fault code.

After a month I didn't had any fault lights on the board but when I scanned the car the same fault was stored ?? So have cared on driving for months without any fault light.

Today the light pop up and ofc is the same fault code...

Is that mean that the replaced Nox sensor could be faulty as well ( if so why the fault lights didn't pop up only was stored ? ) or there could be a any other reason why the same code keeps coming up ? Something else could cause the Nox to get faulty ?

My Car : 2016 S205 C class c220d 651.921
Hope someone had the same problem.

Many thanks for all comments

Adrian