Code P0404

Helmwurst · June 4, 2009

How do I troubleshoot code P0404 on a 2001 1500 Z71? Truck has 178000 miles on it. I reset the code and drove it to work yesterday , no code. When I left work yesterday, the service engine light came on and I scanned it , came up with code P0404 again. After I looked at the ERG Valve, it looks like there may be a bad gasket where the tube goes into the exhaust manifold. Do you think, I should remove the EGR valve and gaskets, clean the valve and replace the gaskets before I take somewhere else or what?

bill190 · June 4, 2009

It would seem to me that the engine computer is telling the EGR valve to move to a certain position, then via a "feedback circuit" from the valve, the engine computer can verify that the valve in fact moved to the position it was directed to move to.

But if the valve did not do as "it was told" (bad valve!), then this would set the error code.

With that said, this could be a bad valve which needs replacement or could be a problem with a poor connection on the EGR valve electrical connector, or could be a broken or shorted wire going to the EGR valve.

So I would inspect the wiring and connector (look inside for dirty contacts), if it looks OK, then try replacing the valve.

Helmwurst · June 4, 2009

It would seem to me that the engine computer is telling the EGR valve to move to a certain position, then via a "feedback circuit" from the valve, the engine computer can verify that the valve in fact moved to the position it was directed to move to.

But if the valve did not do as "it was told" (bad valve!), then this would set the error code.

With that said, this could be a bad valve which needs replacement or could be a problem with a poor connection on the EGR valve electrical connector, or could be a broken or shorted wire going to the EGR valve.

So I would inspect the wiring and connector (look inside for dirty contacts), if it looks OK, then try replacing the valve.

Thanks,

I just saw the other post concerning P0404. I am going to remove the valve , clean and replace gasgets first before doing the 100 bucks deal. I have checked the wiring and everything seems ok, I will clean the contach on the connector when I have it all apart.