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Oct 12, 2004 | 12:14 AM

zachmasaki

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Joined: Oct 2004

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P0401

Just had a code come up recently, after putting in a flowmaster exhaust. Don't know if this is the prob. but could have caused it. I was told the EGR valve was bad, so I replaced it. The SES light came back on 24 hours later and the same code came up. Don't know what to do, can anyone help?

Much appreciative,

~Zach

Last edited by zachmasaki; Oct 12, 2004 at 01:02 AM.

Oct 13, 2004 | 09:41 AM

truckfanactic

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I was wondering if u cleaned the passage out and did u get the code cleared from the computer. It may take a few days for the computer to reset itself. Also u should have replaced the gasket.

Oct 14, 2004 | 02:48 AM

zachmasaki

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well everything is clean inside and out, and the problem was still in effect. It seems I was also supposed to replace the back pressure plate also. It was the switch that has two vacuum hoses running to it and a power cable. it controls the vacuum in the egr valve, from what I was told. Anyway, everything is fine again.

Thanks again,
~Zach

Oct 20, 2004 | 02:13 PM

zachmasaki

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still a problem

Ok I changed the DPFE sensor too and the code came back on, I was told that the O2 sensors could be the problem. I've noticed a massive loss in MPG and power, but the truck doesn't die and runs fine, just real rich. I can't figure this one out, could it be the Diablo sport chip needs to be reprogrammed to suit the new hi-flow exhaust?

Thanks,
~zachmasaki

Oct 21, 2004 | 12:18 PM

wineman691

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same trouble here, this is what I was told

I have had the same code trouble for months. Replaced the EGR valve, as you stated everything was very clean-, replaced the pressure regulator that tells the EGR how much "to apply", and just replaced the DPFE. STILL HAVE THE DAM LOW FLOW CODE. I was told that the PCM is most likely bad and that the dealer can not only test the box but reprogram the PCM as well. Has anyone heard this before or had this done?
Please let me know if you have this done, hopefully my input will stop you from buying all the parts as I have just to get the same dam error again.