Quote:
"A dealership on the other hand would follow the troubleshooting guidelines set out by Volvo and probably would end up spending much more time (labor costs) and replacing the EGR valve..."
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Sorry but I work at a dealership and see that hole being clogged all the time now too. That's the first thing I check when noticing that applying vacuum to the EGR valve does nothing as it should (how it's properly diagnosed btw).
I actually see many very poorly maintained cars that were previously "serviced" by independants so don't assume those w/o factory training and years of real Volvo experience would possibly know more than those who don't. That idea baffles me, unless they're ex-dealer guys.
As for preventative maintenance, I find that those cars with those EGR holes clogged also have clogged flame traps and/or related hoses. That's yet another item that should be checked, cleaned, replaced during routine Volvo maintenance. Frequent oil changes wouldn't hurt either.