C525 pilot reported a partial loss of engine power in cruise. Pilot diverted and landed.

Narrative

Aircraft X with factory installed Williams FJ44 engines. Maintenance on the aircraft is current and has always been performed by Company X. The aircraft is enrolled in an engine program and parts and tech (labor) with Company X. The only recent work on the engines was a desalination wash of both engines at Company X a few weeks ago.On Day 0 at approximately XA:36 Eastern Time while flying single pilot at 41;000 feet I received a CAS message of 'Engine Control Fault R'. I immediately opened the abnormal procedures checklist; which called for turning on the Ice Protection for 2 minutes and then resetting the FADEC on the affected engine. This is designed to clear any ice that may have accumulated on the T2 engine probe. That did not resolve the fault CAS message. At the same time I noticed a gradual loss of true airspeed in cruise from approximately 395 kts to 338 kts and declining relatively rapidly. I advised Center ATC that I was [requesting priority assistance] due to a loss of partial engine power and needed to land. After some back and forth; I was vectored to ZZZ where I twice attempted the approach. The autopilot also would not engage; likely due to strong turbulence. I flew below the approach path at an excessive descent rate at two points during the approach. Weather was not suitable for the approach at ZZZ; so I diverted to ZZZ1 and landed successfully. I contacted Company X maintenance once on the ground. We ran some procedures on the ground; and I read them some fault codes from the MFD and sent data to Company X. They advised me approximately an hour later that they strongly believed that the cause of the message was a failure of the fuel control unit in the right engine. They advised that a precautionary landing was advisable given the decreasing power in that engine. Company X is sending maintenance to ZZZ1 to repair the engine. We will provide a log book entry once that repair is complete. The airplane will be flown by a Maintenance Company X pilot (and me) on the first flight out of maintenance to ensure it is in good working order.I intend to receive additional training on hand flying the aircraft in IMC conditions on an approach and general hand flying techniques.