2003 Merc. S350. coolant sensor.
 

Hi All.
i just put a new water-pump on a 2004 Merc. S350. everything was working fine before that , but after fitting new pump , the orange engine warning, dash light is staying on . is there a certain procedure i have to do , to reset it ? - or has the water-coolant sensor or something else decided to go wrong ? ....
cheers ☺