Focus 1.6 TDCI 08 EML WARNING and loss of power when goin uphill DTC on dash fault is D900 .

This is all I can find from an American Ford site.

The instrument cluster fault code D900 means...." non specific can [url="http://www.justanswer.com/uk-car/1vyen-ford-focus-cel-dtc-xxxxx-d900.html#"][color="green"][color=green !important][font=Verdana,Tahoma,Helvetica,Arial,sans-serif][color=green !important][font=Verdana,Tahoma,Helvetica,Arial,sans-serif]communications[/font][/color][/font][/color][/color][/url] interruption "

This does NOT mean you have a fault on the car. It's merely reporting that the networking around the car had an unidentified interuption in power supply.....so.....had a flat battery or jump start recently ?, maybe battery been disconnected for some reason ?

If the answer is no to the above, then have your battery tested. If battery is ok, have a battery reset done and code should disappear. ( remove negative lead from battery and hold to +ve lead for 2 minutres).

Now I wouldn't hold the negative lead to the positive under any circumstances, but disconnect the battery for about 30 minutes instead. Reconnect, start the car and let it tick over for 5 minutes and then take it for a drive.

If the car does have an issue, its best check for a code via the OBDII Port with a scanner. It should provide a code with more meaning.

Good luck