Vehicle report
Technical service bulletins are instructions a manufacturer sent its dealers about a known fault. They are not recalls and the work is usually not free, but they are the clearest signal of a problem the manufacturer already knows about.
SF191A
VEHICLES EQUIPPED WITH WABCO AIR COMPRESSOR MANUFACTURED BETWEEN MARCH 1, 1999 AND JULY 2, 1999 HAVE EXPERIENCE AIR EXHAUSTING TO THE ATMOSPHERE INSTEAD OF GOING INTO THE AIR TANKS WHEN THE RELIEF VALVE OPENS. THE MODIFICATION CONSISTS OF INSTALLING A PRESSURE RELIFE VALVE OF 175 PSI. *TT
Complaint counts are reports filed with NHTSA, not failure rates. A common model collects more of them than a rare one that breaks more often.