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Ray O wrote:[color=blue]
> OK, I check a factory service manual, and the possible causes of a P0401
> diagnostic trouble code (DTC) are:
> 1) EGR valve stuck closed - you already checked this so this is probably not
> the problem.
> 2) Open or short in EGR gas temp sensor circuit - we'll come back to this
> 3) Open in VSV circuit for EGR - you are getting voltage at the VSV so this
> is not it.
> 4) Improper operation of the VSV for EGR - you already check this so this is
> probably not the problem.
> 5) bad vacuum control valve (VCV) - we'll come back to this.
> 6) vacuum hose disconnected or blocked - hopefully, you already checked
> this. Manifold vacuum should be healthy.
> 7) bad ECM - I've looked at a pretty fair number of cars and have never
> personally run across a bad ECM and I pretty much always toss this cause out
> the window.
>
> You can never mind what I suggested previously about the EGR position
> sensor.
>
> The next step is to check the EGR gas temp sensor. It is located in the
> tube between the EGR valve and the intake air chamber. To check, disconnect
> the wires from the sensor and measure the resistance between the 2 terminals
> on the sensor. Don't do this immediately after driving. Resistance should
> be between 2.5 kilo ohms and 600 kilo ohms. If the ohmmeter reads 750 kilo
> ohms or more or less than 200 ohms, replace the EGR gas temp sensor.
>
> check the wiring to the EGR gas temp sensor to make sure it is not damaged
> or the insulation is nicked.
>
> The VCV for the EGR is located between the intake air chamber and the VSV
> for EGR. There is no electrical connection to the VCV. It is a short round
> cylinder with 2 vacuum hoses. To check the VCV, unplug the vacuum hoses,
> hook up a Mighty Vac to port S and plug port Z with your finger. Pump the
> Mighty Vac 3 times so it reads between 8.6 and 11.8 in Hg, stop pumping,
> wait 10 seconds, and check the gauge. It should read between 4.4 and 7.1 in
> Hg. If not, replace the VCV.
>
> That's about it, if these don't work, I'm out of ideas.
>
> good luck!
>
> --
>
> Ray O
> (correct punctuation to reply)[/color]

For the temp sensor I only have the EGR valve and a tube that goes
right to the engine, there isn't a sensor on it. This isn't the map
sensor mounted on the firewall or one right around the air intake is
it.
I am going to borrow a vac pump today and test the VCV first.
Thanks for all your help.