BMW E46 M54 Engine Coolant Temperature Sensor fault

Hi,

I have 2005 320i E46 with M54 engine and recently started experiencing that she is very smokey during startup and anytime during the day. She does not smoke when I drive though but idles erratic especially in heavy traffic. It's a blueish color and when I did a diagnostic check on her I received fault code "P2185 Engine Coolant Sensor Circuit high". My question to the forum is two fold.
1. Could the ECT cause the smoke and the erratic idling
2. Can I DIY change the sensor on a quiet day

Any feedback and advice will be appreciated!

Thanks

Jacques