As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 2117. BOTH LAVS WOULD NOT FLUSH DURING FLIGHT. LAV TANK LIGHT INDICATES FULL. DIVERTED AND MADE A UNEVENTFUL LANDING. REMOVED WASTE TANK FULL-LEVEL SENSOR. INSPECTED AND FOUND WASTE-TANK "FULL" LEVEL SENSOR TO BE DIRTY. CLEANED AND REINSTALLED SENSOR IAW E175 AMM 38-32-20-000/400-801-A. INSTALLED NEW O-RING REF MCN E380003-001 ISSUE 1. OPS TEST: GOOD. NO FURTHER DEFECTS NOTED. RETURNED TO SERVICE.