As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RNO - FLIGHT 9851 - WITH WING AI ON AND COWL A/I ON RECEIVED A LEFT BLEED MASTER CAUTION. LEFT PACK WAS CYCLING ON AND OFF. RETURNED TO THE GATE. MAINTENANCE REPLACED THE NR 1 ENGINE PRSOV. OPERATIONAL CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE.