CODE P0400 - EGR flow malfunction
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TECH Regular
Joined: Sep 2008
Posts: 443
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From: tampa
CODE P0400 - EGR flow malfunction i have had the code for sure once, and (possibly two other times when the data port wasnt powered thanks to the popped CIG/ACCY fuse).
also, i got this code prior to any mods on the car (assuming same code). and now after mods.
the thing that strikes me odd is that i havent had any typical symptoms. idle is normal, its not running hot at all, no knocking of any form... etc.
what would you do?
!EGR or fix it?
if i choose to delete the EGR what would be the negative effects if any? would i need a tune? or would it just cause the SES light to be on until i tune it? if its just the light staying on it woudlnt bother me. i periodicly scan the car anyways.
is there a LT1 specific tech article for deleting the EGR? i have only found some that are LS1 specific? what parts would be needed?
also, i got this code prior to any mods on the car (assuming same code). and now after mods.
the thing that strikes me odd is that i havent had any typical symptoms. idle is normal, its not running hot at all, no knocking of any form... etc.
what would you do?
!EGR or fix it?
if i choose to delete the EGR what would be the negative effects if any? would i need a tune? or would it just cause the SES light to be on until i tune it? if its just the light staying on it woudlnt bother me. i periodicly scan the car anyways.
is there a LT1 specific tech article for deleting the EGR? i have only found some that are LS1 specific? what parts would be needed?
On The Tree
Joined: Sep 2007
Posts: 177
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From: San Antonio, TX
I had the same code a while back. Someone I knew had an old EGR off his car when he upgraded to a 383. I put that one on, reset the code with a handheld and it fixed the problem. If I couldn't have gotten that done for free I would have probably just deleted it. If you unplug it without getting a tune then yes your SES will stay on. If emissions are not a concern I would probably just delete it with a block off plate and when I had a chance get the code tuned out so the light would go off. But if you have emissions...probably should just get it fixed.
herronperformance in my sig has cheap plates, has them for egr and air it you were ever thinking about doing o/r headers. My EGR is messed up too so i'm doing headers this winter and deleteing all the emissions stuff out, i see it at worthless weight. Herron can also tune your computer to tune out the EGR, email shon and he'll let you know a price
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Joined: May 2014
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P0400 EGR Flow trouble code My '97 Firebird Formula recently stored the P0400 EGR FLOW trouble code, triggering the Service Engine Soon light. I keep a V-Checker code scanner in the glove box and reset the light a couple of times. It always came back the very next day while cruising.
I decided to try and do something about it so I got a spray can of carb cleaner, using it to fill up with the small diameter vacuum lines that come and go to the EGR solenoid, and removed and sprayed out the one-way check valve on the driver's side of the engine (one of the EGR vacuum lines ties into this at a three way tee. I sprayed the port for that which leads into the intake as well. Let it sit overnight and drove to work the next morning. So far its made two trips around town and so far the SES light hasn't come on again. Maybe its too soon to tell, I'm not sure yet. Perhaps it was a sticking EGR control solenoid.
If I was correct then the ECU was signaling the EGR solenoid to move the EGR Valve to "open" but the solenoid was stuck so the vacuum never made it to the EGR Valve.
Considering the awkward location of the EGR valve on the F-body (under the cowl) I wasn't about to just change the valve out. I decided to try other things first.
I decided to try and do something about it so I got a spray can of carb cleaner, using it to fill up with the small diameter vacuum lines that come and go to the EGR solenoid, and removed and sprayed out the one-way check valve on the driver's side of the engine (one of the EGR vacuum lines ties into this at a three way tee. I sprayed the port for that which leads into the intake as well. Let it sit overnight and drove to work the next morning. So far its made two trips around town and so far the SES light hasn't come on again. Maybe its too soon to tell, I'm not sure yet. Perhaps it was a sticking EGR control solenoid.
If I was correct then the ECU was signaling the EGR solenoid to move the EGR Valve to "open" but the solenoid was stuck so the vacuum never made it to the EGR Valve.
Considering the awkward location of the EGR valve on the F-body (under the cowl) I wasn't about to just change the valve out. I decided to try other things first.
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Registered User
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Your comment is helpful to nobody Common for long-time users to totally forget that people search for solutions to problems they have and come here seeking solutions. Old thread or not makes no difference whatsoever. This is why threads don't just disappear after a month or two, SA.
