EGR/DPFE exhaust smell

[burt ragio]

I have a slight smell of exhaust fumes that enters the cabin when the heat is on just enough to be annoying. I have checked & recheck the entire exhaust system & no leaks. I have checked the pvc valve & hose.My only guess is something in the EGR system.
What can I use to clean the egr valve brake or carb cleaner ?
How do I check egr solenoid ?
How do I check DPFE diferential pressure switch ?