[20 Grand]

I have an E93 2008 335i convertible with approx. 56k miles. I've owned the car approx. 8 months. My problem began occurring around 2-3 months prior, but only happened once or twice, then went away. The service engine light came on along with another symbol this past Friday and appears every time I've driven it since. I don't know the name of the symbol, but it is shaped almost like a cylinder or a grenade that is positioned side-ways that is displaying half-full/half-empty. I took the car to my brother-in-law's shop and it came up with codes 2a87, 3100, & P0015. He gave me a print out which says it could be either: Camshaft Intake Position Sensor, Vanos Solenoid, or the Vanos Seals. The service engine light and symbol come on and off intermittently. When the symbol comes on, the car loses a lot of power, but is still drivable. He says he doubts it's the seals. He recommends that we start with changing the sensor and changing the oil, and fill to the full level; however, the current oil level is one notch below full. He recommends that we start there. If that doesn't work, he says to clean the solenoids. Has anyone had this happen? Any suggestions or recommendations to a fix? What was the diagnosis? Thanks, all help appreciated!!