how to check Egr valve

2001 Impala has thrown an EGR code. Sometimes this is just due to other parts in the EGr system, so I don't want to change a 175.00 part, just to see the light come on again. I have a snap on scanner, and was wondering how I might check the voltage, and, or operation of the valve.
It moves up and down freely, and is not restricted in any way, but I have heard that these go bad pretty often. blane

hello, what code is stored

The EGR code is p1404 synigfying that the EGR system is sending a wrong, or lacking signal to the PCM, in which the PCM then sends signals somewhere to not let the car full throttle, but cuts out around 3400 back down to 2800 and back up again.
We have disabled EGr in the past, but that is impossible anymore. So I need to know how to check the voltage of the EGR. If it is getting no volts or sending no volts, I would like to know why before I go spend 175.00

Chrevrolet even recommends that a PCM reprogramming be done after an EGR replacement or a good cleaning. This collaborates the fact sheet from carfax that says the PCM lacks the ability to reprogram itself as most other defaulted systems have sort of a relearn system, which their computers reprogram themselves.
This 2001 Impala has no such relearn system, so if I do fix the EGr, I will still have to take it in and get the PCM reprogrammed. This is nonsence, but what do you do??

Hello sacred,not sure this will help but....
http://www.gearchatter.com/viewpost13032.php
im sure you've done the basic test checking clogs ect.hope it helps
GOOD LUCK
BTW what engine do u have??

The snap on scanner with the domestic engine scanner cartiage has some test you can do to see if it is reading actual closed position to actual comanded position.

I think there is a tsb pertaning to the code where the pcm may need a reflash to correct the problem .
Butr it is a dealer deal on reflash.

I have a 3.4 on a 2001 Impala. I really liked that schematic. Thanks.


My scanner is reading 0.41 volts on a closed Position. This is steady and never moves or opens. The desired is 10.0 the commanded is 0.00.
So one of them says -10. So I think the PCM is not doingright.


I had thought because the scannr kept saying closed that the EGr was bad, and that, because it would never say open. But I think now open/closed is not the issue. The amount of the desired and the commanded need to be the same.
I will go run more test on the wiring circuit. My question now is, if the PCM will have to be reprogrammedby the Dealer, how am I to know if when the dealer flashes the PCM, it will not fix the problem I have now??

I guess that is the luxury of being employed by GM, to be able to continue to flash between test.

What if I took it to them now and they flashed it and it fixed the problem and there really never was a problem with the EGr, or the problem corrected itself, and the PCM refuses to admit it and wants a flashing??

The only way I see to answer this is, either go spend 90 dollars and see, or do every conceivable test untill I pinpoint the knowledge to be that of a signal not being sent by the PCM.

If it were not for the code keeping on coming of p1404 telling me that the EGR system is failing, then I would not assume the right to be going brain dead over a 90 dollar problem........

Off to the test field. I think me having a scanner is a curse.