Check whether the list is null or not

you can check for null as below

if(FaultValues!=null)
{
   //FaultValues is not null
}

if you need to check whether the list having any items

if(FaultValues!=null && FaultValues.Any())
{
   //FaultValues is not null and having items 
}

or

if(FaultValues!=null && FaultValues.Count>0))
{
   //FaultValues is not null and having items 
}

if you need to check for zero items,
First check for null list then check for item count

if( FaultValues!=null && FaultValues.Count==0)
{
   // zero items 
}

Quote:

I forgot to mention that list is not a string but List _lstTempSeverityImg; an image

if it is an image then why you need List? do as below

Image temp;
//when you need to check for null
if(temp==null)
{
  // image is null
}