I purchased my roadster about a month ago, & the engine & transmission seemed to operate fine on my test drive, but now my transmission continually goes into limp mode. Several days ago I took it to a local transmission shop, & they got back with me today with results from their code scan: P220A (N2-N3 Speed Sensor Mismatch) & P2200 (N2 Input Speed Sensor Circuit) along with an engine code P0715 Transmission Control SYS. I have cleared these codes several times, but the transmission continues to go into limp mode after 20-30 shift cycles. The shop recommends a complete transmission overhaul, but since the transmission seems to operate fine once these codes are cleared, I do not think a complete overhaul is necessary. I have read that a conductor plate should take care of the P0715, but what about the others?

 

The speed sensor is on the conductor plate so that needs replaced. While you are doing this also replace transmission adaptor plug (these leak overtime). Inspect the cables from the plug to see if transmission fluid is seeping into them.
The trans fluid can travel up these cables into the TCU. If this has happened, you can try to clean the TCU with electrical cleaner but more than likely will have to replace TCU. You can order kits that come with conductor plate, filter, gasket and adaptor. A complete rebuild of the transmission at this point tells me you need to find a new transmission shop.

 

Thanks for the info. I did check the TCM, & it was dry, but I cleaned it anyway. I guess it's time to purchase a new one. If I purchase the same part number (A0335451232), will I need to reprogram?

 

First thing I would do is replace the conductor plate. That has the speed sensor on it. They are known to go bad. There are threads on the forum about the TCU and part numbers, I do not know that of the top of my head. With a new to you car never a bad idea to change the fluid anyways.

 

Thanks for your help. I will let you know how this turns out, but the shop says they are backed up for 3-4 weeks.

 

Find an Independant shop that works on Mercedese. You have a 2003 Mercedese SLK320 mechanically. You don't need a trans shop to do the conductor plate.