EGR flow excessive

[californicated]

My CEL is on trouble code p0402 EGR flow excessive can anyone tell me what i need to do to fix this and what causes a EGR flow to become excessive i keep blowing a hose that is on the EGR tube

 

[RonD]

EGR valve may be stuck open or EGR tube may be blocked.

There are two hoses that run from EGR tube to the DPFE sensor, mark their locations, at BOTH ENDS, and then remove them and make sure they are clear and air tight, they must be reconnected the same way as removed.

DPFE sensor measures the pressure difference between these two hoses and sends that difference to the computer.
When EGR valve is closed pressure in the EGR tube should be equal at both hoses
When computer Opens EGR Valve the hose closest to the EGR valve will now have a lower pressure than the one father away.
Computer can tell by the pressure difference how far open EGR valve is so can tell how much exhaust is flowing into the intake.

Excessive flow means pressure difference at DPFE sensor is too high.
So could be one of the DPFE hoses
The DPFE sensor itself
The EGR valve
or the EGR tube

Free things are cleaning the hoses and then cleaning the EGR Valve and EGR Tube

 

[naford]

I think in the tech section there is a really good article on how to test the DPFE.

 

[californicated]

Hey, Thanks, Ron Over the weekend I proceeded to remove the EGR valve and the EGR valve After an hour I finally got that sucker off the truck it was a real MOFO to say the least. I was able to blow air through all the tubes on the EGR valve so no blockage in the tube. You say the tube closest to the EGR valve should have equal pressure when the EGR valve is closed,and when the EGR valve is opened the tube closest to the EGR valve will have lower pressure than the tube that is furthest. I wonder if i have them tubes crossed going to the DPFE sensor the one that is closest to the EGR valve is the hose that I keep blowing out,I will test my EGR valve and DPFE sensor later after work to see if they are bad or stuck open I will let you know the outcome thanks, Ron, your help is appreciated

 

[RonD]

Yes, EGR parts are a bitch, exhaust has water vapor in it so rusts parts from the inside out.

Exhaust system pressure is fairly low and actually goes into negative pressure in the mid-RPM range.

The hose "blowing off" could mean your exhaust system has a blockage, creating a back pressure, no 4-stroke engine can run well with any back pressure.
I would tap on Cats and Muffler to see if you hear rattling of loose plates inside.
A sign of blockage is loss of power at higher RPMs as back pressure builds up.

A vacuum gauge can also be used to diagnose limited exhaust flow.

The Hose hook up ports are slightly different sizes at both ends so match them up for correct order.
If you had the larger hose hooked to smaller port it could "blow off"