I had the same problemwith my 94 SL500. I took my car to the local MB dealership in Columbus and the ran a test and it was again the Upshift Delay Valve (about $275.00 in parts and 4 1/2 hrs labor at $110.00/hr). My mechanic said that it reads the catylic converter heating up. Again, he told me like all othres that it is just fine to run the car without replacing this valve. He cleared the codes and so far the Check Engine light has not came back on. Only has been a few days though.

Roger Gray
128,700 miles

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Roger M. Gray