switchover valve & EGR issues
 

Less than a week after returning from the dealership (new head gasket, timing chain, tensioner, rails, guides, belt and belt tensioner), the 'Check Engine' light on my 1993 300E2.8 has reappeared, and I pulled code 26 (upshift delay switchover valve) from the diagnostic module.

I want to confirm that this is the switchover valve before I start some vacuum diagnosis tomorrow (engine is still warm, and I believe I need to do this when cold):

http://smharr4.dnsalias.net/switchover_valve.jpeg

The other code I pulled was code 5 - EGR malfunction. Could this be something as simple as a blocked tube (it was apparently disconnected, and the dealer reconnected it). The tube they pointed out seems to thread a different way around the engine than some of the other photos I've seen - this one starts under the air intake manifold and threads around the front of the engine, but I've seen others thread around the back from the AT dipstick and then back to the manifold - am I looking at two different tubes?

I slept on this, and it strikes me that both of these are emissions related - could there be an underlying cause for both problems?

Anyone?

1995 mercedes c280 inline 6
 

having same issue no vacuum to egr and code p1700 (upshift delay switchover valve) any input anyone? Really need some help thanks!