By searching the discussion forum, I learned that by pressing the button for 3 seconds (with the engine off and the ignition in the on position) and releasing, you count the number of flashes for the fault code.

I got 26 flashes, which would be the same code as last time, the upshift delay valve.

I determined that the green vacuum line was plugged, so I unplugged it, and replaced the switch (a $30.00 part).

Why would the code come back on?

I know that the upshift delay valve is working because it does keep my transmission from shifting into high gear when cold.

The only thing I can come up with is possibly the switch is not getting enough vacuum to work.

Does this make any sense?

I then cleared the code by pressing the button for 8 seconds and then releasing. The Check Engine light is now off.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".