What was found
PRESN AUTO FAULT ANNUNCYATED DURRING CRUISE. LANDING ?P 0.2 PSI. CABIN ALT 2,100 FT DURRING DECENT BELOW 10,000 FEET. LANDING FIELD ELEVATION 2,400 FT. REMOVED FROM SERVICE. INTERROGATED CMC, FOUND FAULT 21311009CPC. C/W E175 FIM 21-31-00-810-819-A. NO DEBRIS NOTED AT OUTFLOW VALVE, FUNC. TEST OF CPCS CONTROLLER CHANNELS GOOD. FAULT CLEARED AND DID NOT RETURN. RETURNED TO SERVICE.