HELP - NOx Sensor
 

I own an A3 1.6 FSI 2004 and i am experiencing some problems. More specifically the the diag. report showed the following errors:

17441 P1033 Sensor for NOx-G295: signal too small
17449 P1071 NOx sensor-G295 heating control signal: implausible signal

I realize that there are 2 sensors (front and rear)and i have to replace both of them. One of the sensor is accompanied with a chip.

Does anybody knows how can iorder these parts (part numbers, a website e.t.c.)?

Thaniking you in advanced.