Upshift delay code is 26--has nothing to do with O2 sensor. Upshift fault can be caused by something as simple as a leaking vac line--might want to check that first before spending money on replacement upshift delay actuator. (By the way, many owners disable the the upshift delay system as it is considered a bit of a nuisance.....)

J. M. van Swaay

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1994 E320 Wagon, 230,000 miles
1995 E320 Sedan, 106,000 miles
1994 E500 Sedan, 79,000 miles