The upshift delay valve is on the side of the transmission.
There is also a switch over valve mounted on the fire wall behind the brake master cylinder.
99% of the time this code comes up because the upshift delay valve no longer holds vacum.
You can check this by pulling the green hose off of the switch over valve, and pulling vacum with a mighty vac. If there is a vacum leak, the pressure will bleed off immediately.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".