too little flow on the EGR Valve on 1999 Chevrolet Lumina

I have had my EGR valve replaced and the service engine light still will not go off. The code I keep getting is P0401 and it is saying too little flow on the EGR. How can this be fixed so my car can pass the emissions test?

by in Saint Louis, MO on March 11, 2011
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1 answer 1 comment
ANSWER by , March 11, 2011
The EGR on that engine uses an electronically controlled Linear EGR valve. The computer looks at coolant temperature, throttle position and air flow meter information to decide when to operate the EGR valve. If everything is correct and the valve is receiving a signal to open (and opens) then the passageway must be restricted or blocked. It's a five wire valve hard for you to test without a wiring diagram and test procedures. Autozone have some popular workshop manuals for free on line once you register (for free) on their website and get an online repair manual subscription.
COMMENT by , March 11, 2011
Do you think it is carbone build up and if so what can I use to clean it out?