Fault Code 26 - Now what? (PICT!)
 

I have a CE light due to an code 26 error. I understand it means an upshift delay switch problem, that is probably vaccume related. Here is a pict of some lines behind the master cylinder. What do I do/check? BTW the car is shifting fine. I have experienced no problems as of yet.

Here is the PICT NOTE: its kinda big

BTW I've got a '94 E420.

Code 26 on that car means that the transmission didn't stay in gear long enough in the morning to properly warm-up the catalytic converter. There is a vacuum element on the trans control pressure cable that controls that delayed shift in the morning.

There is a tremendous amount in the archives on this issue that show you how to troubleshoot this issue.

Play with the search function and you should be able to find a lot of information.

My local MB mechanic tells me that 90% of the time, and upshift delay valve code is usually caused by a vacum leak in the upshift delay valve, located on the side on the transmission.