On a roll at the moment;
1. Trouble with air suspension recently, front of car on the ground, turned out to be faulty height sensor at the front, problem solved
2. Park brake fault, code c1799, turned out to be a bad wire between the motor and module, new wire installed, problem solved..

NOW I have a check engine light, Phew!!
My iCarsoft scanner won't read trouble codes from the engine module, it never has for some reason. Used a generic code reader and its showing P1646. I understand from searching that this is bank1 upstream O2 sensor heater circuit failure/fault. I can read live data with the iCarsoft if needed.
Before I shell out best part of 200 Euro on a new O2 sensor what else should I be checking as a possible culprit (other than the sensor) for this code?
Any advice on this gratefully received

 

A correct Denso O2 should be quite cheap.

 

I had a sensor fail some time ago and can't remember which one it was
but there was a huge difference in price between the pre and post sensors
Refused to pay stupid money and fitted an used one