A missing flapper will cause a smog check failure. The fuel pipe restrictor is an "emissions" component for the purposes of a smog inspection. If a vehicle's fuel pipe flapper is missing, the smog technician will need to indicate "defective" during the part of the smog inspection when he/she is asked about the condition of the EVAP system. The technician may also "pass" the EVAP system and mark "defective" for OTHER (they will then indicate which OTHER emission component they are referring to on the VIR; in this case the Fillpipe Restrictor).
