The EG30xx and EG4xxx are only certified to be used with current transducers (CTs) as described in the section B.6 of the EG30xx Owner's Manual or section B.6 of the EG4xxx Owner's Manual, respectively. Connecting any other sensors can be dangerous, and will void the eGauge hardware warranty.
CTs that are not officially supported but output 333mV from 0-100% of their maximum current rating should function as intended with the eGauge. However, eGauge cannot make any guarantee that these readings will be accurate. These CTs may still cause damage, which would not be covered under warranty.
CTs that output any other type of output signal (including 500mV) will damage the eGauge permanently. This damage is not covered under warranty.
No other sensor type may be connected to a CT port - even if the output signal is 0-333mV, the eGauge has no way to reliably interpret this data. These types of sensors may cause damage not covered under warranty.