I'm not Trent qualyfied either, just a humble CFM56 powered A320 driver.
CFM56 is a fully FADEC engine and doesn't have idle detents/solenoids, however there are about a dozen of different idle settings (ground, air, eng anti-ice, full anti-ice, OEI, approach...), calculated and set by FADEC. Most of them are not even mentioned in our flightcrew operations manuals.
I guess software error or undetected fadec fault would be the equivalent of faulted solenoid of the classic engine.
Also I assume that other FADEC engines are similar in operation to my CFM, but I could be easily assuming too much.