As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN POWER WAS ADVANCED FOR TAKE OFF, A MASTER WARNING ILLUMINATED AND AFT, LEFT PAX DOOR INDICATED UNSAFE. REMOVED FROM SERVICE. REMOVED AND REPLACED THE AFT PAX DOOR LOCK SENSOR IAW WD 52-10-00 IAW AMM 52-71-01-400-802. NO DEFECTS NOTED AFTER AN OPS TEST. RETURNED TO SERVICE.