O2 Sensor heater failure

hi there i have 2002 bmw 325i with the engine light on i when to autozone the codes are po155 02 heater circuit bank 2 sensor 1 and po135 02 heater circuit bank 1 sensor 1 i replace tow o2 in the manifold but when i check in the machine give me a new code p0030 its that normal or the new sensor has a malfunction some vary know exactly the location of this sensors thanks in advance

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This post was auto-generated based upon a question asked on our tech article page here: Pelican Technical Article: BMW 3 Series (E36) Oxygen Sensor Replacement

[Wayne 962]

The heaters in the O2 sensors are only used to heat the sensor when the car is cold. In general, a failure of the heater circuit will not affect the performance of the car too much - mostly when it's stone cold. The fact that you are getting additional error codes right now is probably not related to the replacement of the O2 sensors, I would guess. P030 is the same code - heater element - I would reset the codes and see if it returns.

- Wayne