Duramax egr problems

R

Rambo1

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Mar 30, 2011
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47
First don't know if it is an lly or lb7 but it keeps throwing a po402 I cleaned the mass air didnt come on for about 800 miles. It has a k&n intake & 5 inch turbo back exhaust need help dealer says nothings wrong
 
What's the 8th digit of the VIN ? P0402 is egr flow excessive. It will set a p0401 with the converter removed sometimes. 402 may be just the valve bad, I'd disable it if you don't have emissions testing in your area.
 
You have an LBZ. You're getting that code b/c of the cat being taken out. More than likely it started poping up shortly after the cat was taken off. It's true there is nothing "wrong" it's just that the computer senses too much flow getting out and throws the code.

Do a PPE tuner and that will solve all your issues.
 
It still under warranty it has had the exhaust on it for 2 years never a code until now
 
huh weird. The PPE is a tuner that will automatically block the EGR codes from coming up. Plus give you better power and fuel economy.
 
Does anybody know if this could be possible I'm in the market for a ppe as well
 
When there isn't the back pressure to the egr, you get the code. Why don't you have the correct back pressure? You changed the exhaust flow to a less restrictive setup.
 
That code with a exhaust and intake will get you nowhere under warranty In my shop. What is happening is the maf reading is dropping beyond a calculated range when the egr is on.

Any moron at the dealer that thinks he can fix this with any gm parts shouldn't be trusted to work on your truck.
 
Any reason why it just came on had the intake and exhaust about a year
 
I don't have a real solid answer as to why they go sometimes years without issue but then have problems. I do know what you have going on is pretty common.

Sent from my iPhone using tapatalk and this annoying ass signature line!
 
Thanks for the info with the tuner do I have to block or remove the egr
 
It's not required but I would block it. many vendors including Kennedy and PPE have blocker plates available
 
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