P0401 caused by Aftermarket exhaust?

[Crazyhorse]

Sorry that my first post here is asking for help, but I'm trying to get answers to this, and a certain other board keeps deleting it because I may have at one point removed and reinstalled the cat (the cat in is making this problem worse)

That's what the dealership is telling me now, since they can't find a problem. For 90,000 miles the truck ran perfect, and never threw a code with the MBRP duals with cat delete. At 90K it went in for the mandatory (by the state of California) 06E17 recall and got the latest flash. It has now been in 5 (maybe 6) times since then for a variety of issues (lost of power, loss of fuel economy, higher EGT's, higher trans temps and a boiling sound when you lift out of the throttle). The only code that keeps coming up is P0401. They cleaned the valve, then replaced it the next time, and are now telling me that everything is normal, and that the exhaust is causing all of my problems, but they can't answer as to why it never had the problems before the reflash (it's a coincidince according to them).

Is this a code that can be triggered by free flowing exhaust, or are they blowing smoke?

[Ditty]

How far away from the CA border are you? I would take a little trip to an out of state dealer and get it reflashed by them. I think it's CA's MANDATED reflash that is goofing it all up.

Though...someone else that knows more will be along shortly.

Ohh...and your post won't get deleted here. We LOVE deleting cats and mufflers over here. It just sounds so durn good!!!!

WELCOME TO THE .ORG!!!!!

[rankroddin250]

id just get a tuner and burn them crappy california emmisions tunes off your poor computer.

[SCUFFY828]

do you have an aftermarket air filter , p0401 as nothing to do with open exhaust by the way

[Crazyhorse]

Nope, truck is stock except for MBRP duals, usually w/o cat (it's been going on for every trip to the dealer, and we've tried leaving it on to see if it helped, it hindered instead), guages, and 255 tires in place of the stock 235's. I've thought about a tuner, but worry about the heads, especially since we use this truck to tow in the sierras (some grades we tow regularly are rather steep and long, which seems to cause high EGT's as is, W/O a tuner...

[SCUFFY828]

Originally Posted by Crazyhorse

Nope, truck is stock except for MBRP duals, usually w/o cat (it's been going on for every trip to the dealer, and we've tried leaving it on to see if it helped, it hindered instead), guages, and 255 tires in place of the stock 235's. I've thought about a tuner, but worry about the heads, especially since we use this truck to tow in the sierras (some grades we tow regularly are rather steep and long, which seems to cause high EGT's as is, W/O a tuner...

like i said before , exhaust has nothing to do with it , p0401 is insifficient egr flow , which the majority of the time ends up being the egr valve itself, a clogged up egr cooler can cause this code , and a intake that is clogged ive seen cause it , sounds like they dont have a clue what to do next so they are just telling you that cause they cant fix it , there was another thread on this exact same concern , about a month ago, and i wish i could remember what the outcome was , i will look back and see if i can find it and will get back to you

[william_04_x]

i answered you "over there" too crazy horse...

my dealer did everything to clear the code(including REPLACING the egr cooler) and i still throw that code...

temp differential between IAT1 and IAT2 gives truck EGR flow "proof"...you might have a dirty IAT2...

no big deal though...if you can identify and clear the code you'll be fine....it's a PITA, but nothing to worry about..