Johndr

Thank you for your thoughts. This unit as seen in the pic was removed as it would not cancel the yellow warning light that says there is something wrong with the air regulation/turbo system putting the system into "limp mode". I first had replaced the waste gate actuator replaced and when that didn't do anything positive (cancel limp mode) and I had to have (was advised by a brillant mercedes mechanic who I have known for years) a complete new turbo input system. This replacement (of the turbo system complete) fixed the running issue (no limp mode and no yellow warning light. So what you see in the pic above is what was removed and was faulty and somehow was responsible for the "limp mode". I checked all parts of this unit (as above) and there was no wear in the waste gate pivot bearing nor any wear apparent in the turbine bearings. There was a good deal of stiffness in the operation of the waste gate actuator and from my sense of geometry, in order that the actuator operate smoothly the actuator rod must be exactly in line with the bushing on the actuator otherwise resistance will be experienced as the rod moves backwards and forwards opening and closing the waste gate which I suspect (notwithstanding expert views) has caused the basic problem of air/ turbo speed and "limp mode" I don't know the inside layout of the actuator but suspect that the rod is moved backwards and forwards by a solenoid in accordance with air /turbine needs. It is a vertical structure so it maybe that the actuator is geared in some way to acheive waste gate control. The car has only done 50 000 miles and should show little wear- which seems to be the case on checking the bearings and waste gate pivot bush (no sideways play). There is no provision to adjust the angle of the actuator to achieve accurate movement. Or it could be that I have not got to the root of the problem. Obviously something was done in the past- who by and why is now lost in the mists of time. Your expertise would be most appreciated. Thank you for any thoughts. Regards Johndr

Please comment about what you see in the photo below. The waste gate sticks and causes EPC to light up. The actuator is new and could not move the waste gate coupling. Full replacement necessary. John.

This EPC fault won't go away. Replaced the servo unit that moves the waste gate that governs the turbo speed and manifold pressure. Still has EPC fault??? Anyone have any ideas. Could it be a Computer unit fault???