Expert: Sean Halliday - 12/29/2009

Question
QUESTION: I have a 02 buick century 3.1L v-6, it is showing a code of P0401 Insufficient flow to egr. I was told to clean the passage on the intake, I have done that twice, had the computer reset both times, and light comes back on with same code. I have been using a coat hanger and removing the egr valve and entering through the opening where the egr bolts on. Is there some other way I should be entering the passage? I have sprayed compressed air into the pipe from the exhaust and it is open, and I have also sprayed carb and choke cleaner in the throttle body and the opening where the egr mounts. any help will be greatly appreciated, thank you in advance.

ANSWER: If this engine has the egr position sensor,then it is likely to be the fault.Look also for broken vacuum lines and the egr must be tested correctly as by the book before replacing any parts.

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QUESTION: I have looked and can't find a egr position sensor, looked at the vacuum diagram under the hood and it wasn't listed there either. can you tell me where it should be? and possibly what it looks like?

Answer
No sensor means a fault in the egr valve itself.Make sure it is working by putting vacuum into the in port and see if the engine stalls.This means the valve is ok and you will need possibly to remove the egr valve and clean the metal pipe and manifold port.