These cars are a lot easier to work on than W124's. Having owned nearly 15 W124's and countless W210's, I favor W124's for build and W210's for tinkering.
Okay you have some digging to do - these are fairly simple engines when it comes to vacuum related components.
There are a few intake resonance flaps that are vacuum operated throughout the cars rev range.
P0200 is an "injector circuit malfunction" which will be one of the following:
Fuel quantity actuator (Y23/1) HHTP1220
Fuel rack position sensor (Y23/1/1) HHT P1223
Shifting induction pip switchover valve (Y22/6) HHT P1475
Resonance intake line switchover valve (Y22/7) HHT P1476
Engine control Module (IFI) (N3/7)Or Fuel metering actuator (Y23/1k1) or fuel rack position sensor (Y23/1/1) HHTP1614
Engine control Module (IFI) (N3/7)Not properly coded. HHTP1617
What you'll learn is that the code generally doesn't have anything to do with anything injection related. The code is most likely being thrown by one of the flaps not operating correctly (not hitting limit switches do to soot) or vacuum leaks. Do yourself a favor before spending obnoxious amounts of money: Remove the entire intake system and clean it thoroughly! Apply vacuum to every flap and make sure they're not sticking and that they hold a vacuum.
That flap by the EGR is generally activated at idle. It closes for a bit to stop fresh air flow so the system sucks in EGR recirculated air instead. If it's not working properly, you may get the CEL for EGR or what you have, P0200. There are two more flaps - one in the crossover tube and one in the bottom center of the intake, often times these get stopped up and will throw your code.
CLEAN CLEAN CLEAN! Renew your vacuum lines at the same time. This entire fix is generally free cleaning (material cost) and a couple bucks for vacuum line.
If you were near me I could hook your car up to the HHT and show you for sure. Here's a boring video of me hooking up and going through some diagnosis for resonance flap stuff on my own 97 E300.
https://www.youtube.com/watch?v=yiTOBHO8nRM
As for P0600, is K40 relay problems I think. I don't know where my fault book is so if I figure that one out I'll let you know. lol
It's a diesel Stretch!
