Problem solved, I hope. I used the ICarsoft tool to read the TCM code. It shows 5 stored codes P2560, p229a, p2561, p2511, p2602. I cleared them all then I can clear the odb code 740. Took it out for a test drive, for a 10 miles freeway trip and all is well. Read code in the TCM again and no code. Hope it is a random thing but will research the 5 codes.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.