Installed new sensor for P0155 code and code returns after starting car the second time.

Question

What could be the issue now that code returns after new installed sensor.

Answer 1

P0155 Heated 02 sensor (front) Bank 2 sensor 1

The reason for the code up is power, The PCM controls the on-off of the heater circuit  The MFI supplies power, you will need a voltmeter and test for power, also inspect the harness for proper connection