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Transmission May Leak Fluid and Damage Control Module on Mercedes-Benz E320 CDI

Problem Description and Possible Solution

The electrical connector at the automatic transmission may leak fluid into the wiring harness. If not repaired, the oil will migrate through the wiring harness and damage the transmission control module. A new harness and control module may be necessary to correct this problem.

Problem Data
RepairPal Verified
Average mileage: 140,666 (42,000–270,000)
2 model years affected: 2005, 2006
6 people reported this problem
Viewing 1 - 3 of 3 comments
Just diagnosed yesterday. Erratic/rough shifting transmission has been occurring for over 10K miles. First diagnosis was a torque converter, since the transmission service did not reveal any tranny problems. We have decided to drive it since we were not convinced it was the torque converter. Now, a second dealership has found the oil in the control module. The cost to replace was over the top, and, there was no guarantee that would fix our rough shifting problem. So, we are trying to decide what to do at this point.
I've been struggling to get a recurring transmission problem fixed for over 2 years. First the tranny was reconditioned at 88,000. Since then, there have been elusive shifting problems. Two different repair shops (including the dealer) told me I was imagining things. Finally, after leaving the car for them to drive for a week, they agreed. Now I've been without the car for 3 1/2 months as they struggle to diagnose it. Was told there was oil leakage that damaged the module, but after replacing it with 3 different new ones, they say the module is fine (not sure that's true). Instead they have replaced the torque converter, but I'm still waiting to get the car back . . .
Leak of trans fluid trough electrical connector.