Hi . My name is XXXXX XXXXX i will be assisting you with this issue of your check engine light .As you know the malfunction code can only be cleared once the management system sees that all system are working correctly ,DTC P1646: ECM HO2 Sensor Control Malfunction - Bank 1 Upstream (1/1)
HO2 Sensor 1/1 heater failure
HO2 Sensor 1/1 sensing circuit: short circuit to ground, short circuit to high voltage, open circuit, high resistance
This is normally only a straight forward replacement of the O2 sensor ,but i suggest you have the system first checked with a scan tool , as ECM are known to be the problem in some rare cases..
Need further assistance with this issue then please get back to me .
My goal is to provide you with excellent service – if you feel you have gotten anything less, please reply back with the reply box below and not the poor or bad service button ,For further assistance there is no extra charge after accepting.Rgds Greg