I was recently attempting to change my ignition coils but unfortunately damaged one of the connectors [my own stupid fault] and had to take it to an indy MB specialist to fix. I drove the car 8 miles on seven cylinders and was surprised how well it drove being off one cylinder. The indy rewired the connector but when I called he said the engine was now showing at least 10 fault codes and misfiring on various cylinders and now refuses to start. The car is a 2006 W221 S class with 80k miles which does fall within the range of cars with faulty idler gears. To date there has been no timing chain rattles or fault codes to do with engine timing but the indy thinks it may be a timing issue which he won't know until he takes off the rocker covers. My question is; what could have happened to go from an ignition coil connector issue to a situation where it looks like the engine will have to come out to have new timing chain etc fitted.
The only other suggestion was an ECU issue which somehow developed.

 

Seems it is an ECU failure which is now being replaced.