Kim O

Hi All, I need some advice. My S550 had the ME control unit replaced 15,000 miles ago (10/2019) and now (2/2024) the engine light came on. I took it to the dealership. Initially they told me the engine light was due to camshaft adjuster solenoids. Those were replaced, but the engine light came back on during their test drive. The technicians were baffled, but are now saying that the ME control unit needs to be replaced again. It's only been 15,000 miles since it was replaced last time. It is no longer under warranty since it's been over 2 years. They are quoting me close to $7000 for the solenoids, new ME unit, and some other small work performed on the vehicle. Please advise what else could be causing this engine light. Any suggestions are appreciated. TIA!