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Dan, ASE Certified Technician
Category: Buick
Satisfied Customers: 2270
Experience:  20 Year Factory Trained Current GM Technician
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1999 Buick Century: a trouble code..EGR valve..check engine light

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Hello, i have a 1999 Buick Century. It was giving a trouble code 401 EGR below thresehold. Installed new EGR valve (pep boys brand) reset check engine light. Drove few miles and light came back on and giving the same code 401. Any idea whats going on? Thanks in advance Patrick
Hello <a href="../profile.aspx?PF=31182824&FID=101"Customer

What we see a lot with this cone on this engine is the upper intake gets it passages clogged up with carbon from the egr valve.
To test if this is the issue or not, it requires a scan tool to open the EGR valve and see if the engine speeds drops or dies out. You can remove the egr valve and start the car with the valve off and see if there is a lot of vacuum coming from the port.(same as if the vacuum hose being off of the brake booster) There will also be exhaust noise coming where the EGR goes also.
If it is clogged up, the best way to fix it is to remove the upper intake and take it to a machine shop and have it hot tanked and cleaned. You can try picking at it with a piece of wire but it takes a lot of time and you have to make sure non of the carbon gets into the engine.
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