As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AT 20,000 FT AT MAX DIFFERENTIAL , FORWARD EMERGENCY EXIT DOOR WARNING LIGHT FLICKERED ON/ OFF , THEN CAME ON STEADY. WHEN CABIN DIFFERENTIAL BELOW 4.5 PSI WARNING LIGHT EXTINGUISHED. AIRCRAFT RETURNED TOORIGINATING AIRPORT. MAINTENANCE INSPECTION FOUND FORWARD EMERG EXIT DOOR SENSOR RIGGING EXCEDED MAX ALLOWABLE , GAP ADJUSTED AS PER MM. AIRCRAFT RETURNED TO SERVICE.