I read/update data from MS Access using C#. My code is:
public static void UpdateLastLogin(int userid, DateTime logintime) ///logintime = DateTime.Now
{
Try setting the "DBTYPE" property of the parameter to identify it as a date, datetime or datetime2 as appropriate...
prms[0].DbType = DbType.DateTime;
There are 7 signatures to the new OleDbParameter() call, so you may change the signature instance, or just do explicitly as I sampled above since you only had 1 parameter in this case.