hi i have a 2001 ML270cdi, it developed a problem starting, i.e it wont start first time, then if you keep the key turned for about 45 seconds it splutters into life, once started it starts throughout the day as good as gold, after having taken it to my local Merc garage i was told it was an immobiliser problem and a new key will sort our the problem, so with a new key and 2 lots of diagnostics costs i have the same problem, my local garage (non merc) have found a code (P1831) which he cannot find in his code breaker book, Mercedes cant diagnose the problem, anyone else got or had this issue, is it resolvable.

 

It sounds like one of your O-rings on fuel lines connections is not sealing right letting some air in if not pressurized by fuel pump for a while. Then in the morning fuel will push the air through ( it splutters first, not a smooth start up).
P1831 is nothing to worry about. Per my star manual for 01 ML320 (here in US we have no nice diesel MLs):
Temporary loss of communication between transfercase control module N78 and shift motor ***. Check the operation of your low range gear shifting per owner's manual if it is shifting and light indicator shows the correct operation, your truck is OK.
I believe this have nothing to do with your starting problem but you could post same question in diesel section of this forum.

 

I have a ML320 2001, left in garage for one month, would not start. Full headlights and all seemed ok. Boosted the battery and the car started right away. I think there must be a safe guard for low voltage battery. Once started everything OK.
Check your Battery at rest and running voltage, should be 12.5 and 14.2 volts @ 70F respectively.