As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMBOUT FROM DTW, RECEIVED 'HYD B SYS LO PR' MESSAGE. FOLLOWED COCKPIT OPERATING MANUAL PROCEDURES AND PRESSURE RETURNED TO 1750 PSI. DECISION WAS MADE TO RETURN TO DTW WHERE AN UNEVENTFUL LANDING WAS ACCOMPLISHED. MAINTENANCE FOUND THE BLUE HYDRAULIC SYSTEM CASE DRAIN FILTER DIFFERENTIAL PRESSURE INDICATOR POPPED. REPLACED THE BLUE HYDRAULIC SYSTEM ELECTRIC PUMP. OPERATIONAL CHECK OK.