Generally, no. In fact, disconnecting the batteries and turning the key on (to provide a load) will eventually drain the power from the PCM and the ECM and will clear any suspicious codes. Any codes that are stored are not definitive proof of a fueling box anyway.
If you have an overhead trip computer that calculates MPG, and the average is unusually high, that is a red flag, as is the tapped fuel pump wire. As far as I know, that's it.