Geocoding Zip Code Issues

I am geocoding addresses using the ArcGIS Online Geocoder and Street and Zip Code. In some cases, the geocoder has read the zip code as 4 digits and in other as 5. I got a 99% hit rate, but the addresses not are geocoded correctly as a result of this error. How do I fix this? Maybe add a field for city?

I think a better question would be why is it only reading 4 digits instead of 5? But to answer your question, ArcGIS Online will geocode fine without a zipcode if you have proper street naming, including a N,S,E,W prefix for streets that share an address, and you include the city and state.

Quoted from ESRI:

This operation can be used to find the following types of locations:

Valid Street addresses:

27488 Stanford Ave, Bowden, North Dakota

380 New York St, Redlands, CA 92373