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#2457621 - 12/09/11 01:49 AM Check engine light on 97 GMC Sierra 350 V8 (P1406)
Chris B. Offline


Registered: 03/16/03
Posts: 2960
Loc: Colorado
I was driving my 1997 GMC Sierra today after it has been sitting in storage for 2 months. After driving it around the block the Check Engine Light came on. Everything seemed ok though and all guages were ok. I stopped by the auto parts store and they scaned it for me and found code P1406 which has something do do with the EGR system having a fault. While I was driving home the Check Engine Light went off and did not come back on. I restarted it several times and it never came back on. Did it fix itself?
If it still has this problem or if it comes back is this a hard fix on this truck? Anyone know what I need to do to fix it? I'd like to try fixing it myself if it is not to hard but I'm not a mechanic. Thanks for any help!!!


Edited by Chris B. (12/09/11 01:50 AM)

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#2457630 - 12/09/11 03:12 AM Re: Check engine light on 97 GMC Sierra 350 V8 (P1406) [Re: Chris B.]
Milkman Online   content


Registered: 05/20/10
Posts: 284
Loc: Pittsburgh PA USA
If it ain't broke...
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#2457680 - 12/09/11 07:23 AM Re: Check engine light on 97 GMC Sierra 350 V8 (P1406) [Re: Chris B.]
Jim Spahr Offline


Registered: 07/02/03
Posts: 996
Loc: Lexington, SC
If it is the old style EGR like the one in my 94 Chevy V8, you can easily remove the EGR and clean the pintle and put it back on. Cost? A new gasket for 1.49. Check to make sure all connections are on tightly and in good conditions.
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#2457681 - 12/09/11 07:23 AM Re: Check engine light on 97 GMC Sierra 350 V8 (P1406) [Re: Chris B.]
opus1 Offline


Registered: 12/13/04
Posts: 2046
Loc: Chicago Area
Agree with Milkman to a point.....things that "fix" themselves always scare me. I wouldn't be surprised to see it come back.

Off-the-wall-guess, since the vehicle wasn't run for a couple of months, I speculate the EGR valve was sluggish/gummed up. But until the light comes on for good, I wouldn't mess with it.
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#2457756 - 12/09/11 09:19 AM Re: Check engine light on 97 GMC Sierra 350 V8 (P1406) [Re: Jim Spahr]
cchase Offline


Registered: 11/03/09
Posts: 3999
Loc: New England
Originally Posted By: Jim Spahr
If it is the old style EGR like the one in my 94 Chevy V8, you can easily remove the EGR and clean the pintle and put it back on. Cost? A new gasket for 1.49. Check to make sure all connections are on tightly and in good conditions.


On that older system, oftentimes all you have to do is push it in manually a few times and it will get it working again if its stuck. No disassembly required. I don't think the Vortecs have the same EGR though.

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#2457903 - 12/09/11 12:40 PM Re: Check engine light on 97 GMC Sierra 350 V8 (P1406) [Re: Chris B.]
Chris B. Offline


Registered: 03/16/03
Posts: 2960
Loc: Colorado
Anyone know what EGR the 1997 Vortec 350 came with? I'm not even sure what it looks like of where to find it. I probably need to buy the repair manual before I try to fix anything in the future. I did a google search for the "EGR" but all I could find was other GM models. Thanks for the help!

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#2458326 - 12/09/11 08:04 PM Re: Check engine light on 97 GMC Sierra 350 V8 (P1406) [Re: Chris B.]
ArrestMeRedZ Offline


Registered: 11/11/08
Posts: 673
Loc: Las Vegas
It sits on top of the engine, in the middle, near the front, right next to the thermostat housing. It's round, about 2" in diameter, about 2.5" long. I believe it can be extracted by taking out 2 bolts with 10mm heads.

Mine ('97 Vortec 350) started with the intermittant CEL, and I lived with it for about 10 months until it came on steady. I replaced it to make sure it passed smog. If it can be fixed by cleaning, I've got a spare now.

It may have been my imagination, but I believe I could smell an exhaust type odor in the cabin when it malfunctioned. I also seemed to have gotten worse gas mileage.

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#2458407 - 12/09/11 09:00 PM Re: Check engine light on 97 GMC Sierra 350 V8 (P1406) [Re: ArrestMeRedZ]
Chris B. Offline


Registered: 03/16/03
Posts: 2960
Loc: Colorado
Originally Posted By: ArrestMeRedZ
It sits on top of the engine, in the middle, near the front, right next to the thermostat housing. It's round, about 2" in diameter, about 2.5" long. I believe it can be extracted by taking out 2 bolts with 10mm heads.

Mine ('97 Vortec 350) started with the intermittant CEL, and I lived with it for about 10 months until it came on steady. I replaced it to make sure it passed smog. If it can be fixed by cleaning, I've got a spare now.

It may have been my imagination, but I believe I could smell an exhaust type odor in the cabin when it malfunctioned. I also seemed to have gotten worse gas mileage.


Thanks for the good info!

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#2458436 - 12/09/11 09:44 PM Re: Check engine light on 97 GMC Sierra 350 V8 (P1406) [Re: Chris B.]
wtd Offline


Registered: 06/25/02
Posts: 1280
Loc: southwest Mo.
Take it off and clean it. The EGR valve on the vortecs get quite a bit of carbon on them. On my 98 with the 5.7L, even though I didn't get a CEL, I took mine off anyway to clean it because I was having other issues and mine was very dirty. Make sure to use a new gasket.

Wayne
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#2458524 - 12/10/11 02:30 AM Re: Check engine light on 97 GMC Sierra 350 V8 (P1406) [Re: wtd]
Chris B. Offline


Registered: 03/16/03
Posts: 2960
Loc: Colorado
Do any of you guys know of a website that has a good step by step discription with pictures on how to clean up or replace the EGR? Thanks!

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#2469864 - 12/22/11 12:19 AM Re: Check engine light on 97 GMC Sierra 350 V8 (P1406) [Re: Chris B.]
ArrestMeRedZ Offline


Registered: 11/11/08
Posts: 673
Loc: Las Vegas
Nope, but replacing it was pretty simple. It took less than 5 minutes, if I remember correctly.

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#2470513 - 12/22/11 06:40 PM Re: Check engine light on 97 GMC Sierra 350 V8 (P1406) [Re: Chris B.]
johnsmellsalot Offline


Registered: 07/02/11
Posts: 526
Loc: Texas
This happened to my car too. When I was replacing the head gaskets, I found out that the EGR passage way was completely clogged. It took 2 cans of carburetor cleaner and a coat hanger to clean it out. This guy explains the general procedures. http://youtu.be/XgfT3kuY8lc
Originally Posted By: Chris B.
I was driving my 1997 GMC Sierra today after it has been sitting in storage for 2 months. After driving it around the block the Check Engine Light came on. Everything seemed ok though and all guages were ok. I stopped by the auto parts store and they scaned it for me and found code P1406 which has something do do with the EGR system having a fault. While I was driving home the Check Engine Light went off and did not come back on. I restarted it several times and it never came back on. Did it fix itself?
If it still has this problem or if it comes back is this a hard fix on this truck? Anyone know what I need to do to fix it? I'd like to try fixing it myself if it is not to hard but I'm not a mechanic. Thanks for any help!!!
_________________________
1999 Buick Century 180,000 miles (first car)
2008 Chrysler PT Cruiser 70,000 miles

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#2470566 - 12/22/11 07:49 PM Re: Check engine light on 97 GMC Sierra 350 V8 (P1406) [Re: johnsmellsalot]
partspro Offline


Registered: 12/08/11
Posts: 169
Loc: MO, USA
The p1406 refers to the pintle position. The EGR valve on your truck is not the old style vacuum can. They can be cleaned just don't go overboard with cleaner. While cleaning the EGR passages is always good, clogged passages usually throw an EGR low flow code (p0401 IIRC). Since its an electrical valve the cost is pretty high +/- $140. I'm pretty sure that there is a 'relearn' procedure for this valve using a high end scan tool.

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