I also got a P203A Mod $00 today at around 53K on my 2010 X535d. Based on what I have read, the code might not return for a while after it is reset, which makes it hard to get the dealer to proceed with a fix. My question is should I delete the code and see if it comes back before taking it to the dealer?

The old hound has been running into weird problems lately. Hardly any issues up to 50K but recently, a slew of weird things including this.

There is a similar thread on bimmerfest: OBD-II Diagnostic Trouble Code P203A - Page 3 - Bimmerfest - BMW Forums

I will update both with my experiences. I have an appointment with my dealer next Saturday. Hopefully the extended warranty will prevent a runaround but if they reset the code and it doesn't come back, I'll be down $200 in diagnostics fees and no resolution. Any guidance appreciated.