Let’s hope you don’t have the dreaded “03” sensors that Brian has. See: Ds18b20 and emonTX3CM firmware - #78 by dBC - post 78
If you do find you have those, and you have the old (not CM) sketch, you should be OK if you permanently power them from 3.3 V, rather than using the emonTx’s switched power (labelled DS18B20 PWR).