My speedometer (2000 CLK320 Cabriolet) has a habit of suddenly jumping about 20 mph, then staying with this inflated reading, even indicating 20 mph when I'm at a standstill. When I turn off the ignition, the needle drops back to zero. Generally, the needle action is slightly jerky, but not too bad, until it suddenly jumps.
Where is the signal taken from? Is there anything I can replace?
I've had the instrument cluster out a couple of times to fix the time and temp pixel problem (successfully!) - I'm wondering if I did anything at that time to cause the problem.

 

I asked this question a while back and got no response. Mine does the same thing. The needle almost "ticks" like the second hand on a clock. I have also had it read high and then be ok once the car was turned off and on. It's been a year now and I just learned to deal with it. I don't think it has anything to do with the speed sensor and it is likely the gauge itself. If you put the digital display to show the speed you will notice that it is accurate even when the needle isn't. Wish I had the answer but I don't

 

Thanks - good (in a way) to know I'm not the only one with the problem - You described it better than I did.
My car doesn't have a digital display, at least, not that I know of!

 

I had that problem after disassemby of the cluster also. Fix for me was to just remove the face and press the guages firmer against the circut board. I had the tach and the speedo doing that jumpy thing

 

I have exactly the same issue as Conrad_g. Fixed missing pixels and everything fine, then speedo started erratic behaviour about 200 km later. When needle goes to zero after high reading, I can hear clicking sound. Also, it seems needle gets stuck on higher reading if I brake harder than normal.
Did anyone find an answer? Is it the needle not rotated enough after working on cluster, or are needle gears stripped?Grateful any further info out there.

 

I finally gave up, and found a brand new.cluster on eBay for $400, still sealed up in the MB box, about a quarter of the dealer price, and paid my MB service place to install it, so they could reset the mileage correctly (only possible by a dealer on a brand new unit), so unfortunately, I can't suggest a cure for the problem, other than replacement.

 

You pressed the needles in too much....Take them off and press them down again with slightly less force. Happened to me and thats how I fixed the issue. I also had it happen after I fixed the pixels.

KRis