Nissrolet

Hello all . I'm new to this site and Mercedes vehicles and struggling a bit with navigating the site and the abbreviations commonly being used but I'll get there. Two weeks ago I purchased a lovely 2003 CLK 320 with an impeccable provenance with 165 K on the clock. Test drive was perfect. Since owning her I'm experiencing the following problem. When using kickdown to overtake everything works just fine for a few seconds, it changes down and quickly increases the revs, then there's what I'd describe as a violent disconnection of the gearbox . This is accompanied with total loss of drive, the engine will rev under throttle control but no drive. Taking it out of drive and back in again has no effect.The car has to coast to a near stop and then everything returns to normal.
There are no other issues to report it drives and sounds beautiful. If anyone can suggest a course of action I'd be very grateful. I'm also trying to firm down on which OBD2 diagnostics/ code reader to buy in the $300-$400 range again any recommendations would be helpful. Regards Nissrolet

jimyj

Hey Nissrolet, I totally get how annoying that kickdown issue with your CLK 320 can be. This kind of behavior often points to problems within the transmission system, such as a malfunctioning torque converter or issues with the transmission control module (TCM). It could also be related to sensors like the throttle position sensor (TPS) not communicating correctly with the engine control unit, causing erratic gear shifts. Additionally, low or degraded transmission fluid, or failing solenoids, might be disrupting the gearbox operation, leading to that sudden loss of drive when you push for overtaking. Accelerator pedal can also be the issue. You should probably run a full system scan to get to the bottom of this. There should be fault codes on at least one or more control modules related to this issue. Using a full system scanner like Xentry is ideal if you have access to it. I tend to use youcanic full system scanner since it’s easier and quicker for diagnostics, even though I have Xentry lying around. It can run an in-depth all-system scan and diagnostic, helping you identify the exact cause without too much hassle. Hopefully, it’s something straightforward and not too much of a headache!

JD-CLK

Have you tried replacing the gas pedal assembly?

Nissrolet

No I haven't tried replacing the pedal assembly yet . I have had a really good look at it though. From an appearance point of view it looks like new. Of course I'm not able to determine the pedal position sensor condition internally but it's working and driving smoothly in every other way. Do you know if I'm able to just replace that sensor on the pedal or do I need to replace the whole pedal assembly?