I should've mentioned in my previous post that wendy's MB dealer wasn't thorough enough when diagnosing her problem ( I posted during my very short lunch break).

It sounds as though they decided the oil contamination in the wiring harness would resolve the P0410 fault code (Air Injection). This is where things began to go wrong. I've found that the O2 sensor(s) are usually the first parts damaged by oil in the wiring harness. I wouldn't be surprised if wendy's car had one or more fault codes stored for the O2 sensors.

Concerning the P0410 code, the M111 Kompressor motor has a few known issues that can cause this problem. The in-line check valve would be the first place I would suggest checking. The upstream O2 sensor would be the next item to check (if it wasn't replaced already). In some cases, the Air Recirculation Valve is the problem. Whatever the case, the dealer still has some work to do, and maybe some explaining as well.

The first thing wendy should do, is find out what fault codes were stored when her dealer performed the SDS Short Test. If there were multiple codes stored, they were (for the most part) justified in taking the course of action they did. If the P0410 was the only stored fault code, then the dealer didn't fix the problem that she bought the car in for, they only prevented the "CHECK ENGINE" light from coming on in the near future. If this is the case, and if wendy wasn't told this before the work was done, the MB dealer has a problem.