There is really is no way to be sure the check valve is good so it's best to replace it. The check valves only last so long and are a known issue. You can turn the pump on through INPA or a good scan tool.

__________________
1988 325is (purchased new) sold
2004 X5 3.0 2005 X3 2.5
2008 X5 3.0 (new to me)