Point inside st_dwithin with wrong results

I want to get all points, that are in the same area. Therefore, I have the following query for my table check:

SELECT l.location_id, l.location FROM check l INNER JOIN check l2 ON ST_DWithin (l.location, l2.location, 500) AND l.location_id<>l2.location_id;

The column location is a Geomeotry(Point) data type.

The execution gives me an error and gives me more than 2 million result sets...from initial 1560 rows. The points are normally distributed through Europe and setting the threshold to 500 (m) seem to be fine. Is it may be a prolem with the data type?

Thanks