Hello Peter,
These fault codes are listed by Mercedes as "Event" codes
I don't have a definition for this exact code, But I do for other Event codes i.e

P2BAB00. This relates to excessive nitrogen oxide emission/exhaust gas recirculation rate is too high.

The definition/remedy is,
1, This fault code occurs if an emissions relevant component fails.
2, Process other fault codes first of all.
3, If no further fault codes are present ignor this fault code.

Then there is is a note refering to,
1, This code serves to meet legal requirements of NOx limit etc
2, The fault code is automatically rest after 400 days.

But as I said earlier i don't have information for the P2BAC event code.

Regards,
Ian