As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: FLIGHT CREW REPORTED THAT THE 1L MAIN CABIN ENTRY DOOR INDICATES CHECK DOOR PRESSURE. MAINTENANCE CONFIRMED THAT THE BOTTLE PRESSSURE WAS GOOD AND REPLACED THE DECODER ENCODER UNIT B (DEU) PER AMM 23-73-47. A SATISFACTORY OPERATIONAL CHECK WAS ACCOMPLISHED.