How do you clean an egr valve and where is it located?
Generally, an EGR valve is found high-rear on the motor. They can quit working due to carbon build-up on the internal shaft which causes them to stick in the open position and are hard to clean. Try spraying DEEP CREEP into it to loosen it up, then move the diaphragm by hand. DEEP CREEP is sold by the SEA FOAM companay and is found at marine dealers.
Depends on the EGR valve. A good lot of them can be cleaned and reused. New ones can costs hundreds of dollars. The EGR valve works by routing a small amount of the exhaust gases back into the combustion chamber. See the Related link for more information. To clean the EGR valve, you may be required to remove the vacuum hose and clean out the carbon deposits.