fabriani

I would like to have on my Focus MK3 facelift(2015) the warning snow light as I had on Mondeo MK3 , namely:
- red snow light below 0 degrees Celsius
- yellow snow light greater than 0 degrees and less than 4 degrees Celsius
Can it be done? How?

Now, it only shows yellow, starting from 4 degrees down.

I have read what wjtwjc wrote:

"If you want to get the red and yellow snowflake light just flash BU firmware."

I do not exactly understand what he means. Please, can anybody explain me step by step what should I do?
Thanks.