06 MB e350 4matic check engine light

Took it to the dealer. “Perform 541011 test. Fault codes ME 1200 and ME1208 RT exhaust and RT Intake sensors faulty. Replace RT exhaust and RT intake sensors. Clear codes.” Six days later took back to dealer with check engine light on. “Fault code 1200 in system. replacement of sensors did not eliminate code.” Dealer wants to dis assemble to access sprocket to inspect per dtb. At the same time telling me they have never experienced this before.



What do all these codes mean:

541011 test

ME 1200

ME1208

RT

DTB



Anyone experienced this before?