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#4727070 - 04/14/18 07:50 PM 2001 Impala check engine light on question
JimPghPA Offline


Registered: 08/22/09
Posts: 3824
Loc: Pittsburgh,PA U.S.A.
Yesterday on the way back home the check engine light came on on our 2001 Chevy Impala with 102 K miles on it. Today I stopped in Advance Auto Parts and borrowed their code reader. No P codes came up,

but it did say:

Exhaust gas recirculation flow insufficient detected

Top reported fix 1 - cleaned exhaust gas recirculation (EGR) passages



freq reported fixes:

1 - replace exhaust gas recirculation (EGR) valve

2 - cleaned engine carbon

3 - cleaned exhaust gas recirculation (EGR) transfer tube

4 - clean intake manifold

5 - replace intake manifold

6 - cleaned throtle body

----------------------------------------------------------------------

I looked on youtube for "Chevy 3.4 EGR" and there are videos showing the passageway that is part of the intake manifold that goes from the EGR valve to the intake port, and it shows one that was completely clogged up. This is probably what is going on with our Impala.

I am going to be very busy for the next four weeks then I will have a couple of weeks when I will not be busy. Do any of you see any problems in putting off fixing this exhaust gas flow problem for four weeks and continuing to use the car every day?

The engine runs fine, and I had it inspected last month so there is currently no problem in having the check engine light on for several weeks. I think that if the EGR valve had failed open that it might be something that requires immediate attention. But according to what the code reader displayed there is an insufficient flow of exhaust gas, so basically it failed in the not supplying exhaust gas mode.

So what do you say, does anyone see any possibility of causing engine damage by driving it the way it is for four weeks, about 100 miles per week?
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#4727084 - 04/14/18 08:00 PM Re: 2001 Impala check engine light on question [Re: JimPghPA]
Trav Offline


Registered: 11/20/06
Posts: 18234
Loc: MA, Mittelfranken.de
You may notice slight pinging because the exhaust gases are used for cooling in the combustion chamber and help prevent detonation, if so use the next higher octane fuel, otherwise no problem other than the CEL.

Edit: Give the EGR valve a couple of sharp taps with a rubber mallet just for the heck of it.


Edited by Trav (04/14/18 08:10 PM)
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#4727102 - 04/14/18 08:24 PM Re: 2001 Impala check engine light on question [Re: JimPghPA]
14Accent Offline


Registered: 08/03/17
Posts: 332
Loc: MN
3.4? Clogged passages for sure.

You won't hurt anything until you get around to fixing it. Drive on.

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#4727117 - 04/14/18 08:38 PM Re: 2001 Impala check engine light on question [Re: JimPghPA]
eljefino Offline


Registered: 06/15/03
Posts: 32377
Loc: ME
You might only need 1/2 hour to an hour to get the valve off and see what's going on. Sometimes the pintle hangs up and you can poke it with a pencil or spray brake cleaner in to clean it.

Though I understand not wanting to mess with your ride to work when you're busy.

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#4727128 - 04/14/18 08:50 PM Re: 2001 Impala check engine light on question [Re: JimPghPA]
JimPghPA Offline


Registered: 08/22/09
Posts: 3824
Loc: Pittsburgh,PA U.S.A.
Trav, thanks for the info, and the suggestion to run high octane.

I have not noticed any pinging. Currently, it has a half tank of 87 octane. I will fill it with high-test, and run high test until I can get it fixed.
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Boy will I be happy when ALL vehicles on public roads are autonomous.


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#4727132 - 04/14/18 08:52 PM Re: 2001 Impala check engine light on question [Re: JimPghPA]
clinebarger Offline


Registered: 12/19/13
Posts: 1739
Loc: Fort Worth, Texas
It should have a P0401 stored in the PCM, You may want to have it checked with a better/different scan tool if the AZ one couldn't show such a generic DTC, It's also possible the operator didn't enter correct vehicle info in the scan tool.

P0401 is NOT usually set by the EGR valve itself, GM OBD II EGR valves have a Pintle Position Sensor, If the Desired/Commanded Pintle Position is more than 15% different from the Actual/Read Pintle Position......DTC P0404 will set.

Unless you have a bad exhaust leak.....I would lean toward a clogged/partially clogged EGR passage. ALL the EGR passages (That aren't part of the Valve Assembly) are in the Upper Intake Manifold which isn't to bad to remove & clean.

In some rare cases.....P0404 is not enabled in the calibration, But not likely on a 2001 Impala.


Edited by clinebarger (04/14/18 08:53 PM)
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#4727172 - 04/14/18 09:35 PM Re: 2001 Impala check engine light on question [Re: JimPghPA]
eljefino Offline


Registered: 06/15/03
Posts: 32377
Loc: ME
I legit cleaned the passages in a saturn with electric EGR (same as yours) with a frayed bike brake cable chucked in a drill. It's a cliche but it works.

When you have the valve off, run the motor. If it's not loud with exhaust it's on that end of things. If it idles normally the intake side's plugged.

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#4728242 - 04/15/18 08:20 PM Re: 2001 Impala check engine light on question [Re: eljefino]
JimPghPA Offline


Registered: 08/22/09
Posts: 3824
Loc: Pittsburgh,PA U.S.A.
Originally Posted By: eljefino
I legit cleaned the passages in a saturn with electric EGR (same as yours) with a frayed bike brake cable chucked in a drill. It's a cliche but it works.

When you have the valve off, run the motor. If it's not loud with exhaust it's on that end of things. If it idles normally the intake side's plugged.


That is a great idea on how to troubleshoot what passageway is clogged.
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Boy will I be happy when ALL vehicles on public roads are autonomous.


JimPghPa


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#4731365 - 04/18/18 07:39 PM Re: 2001 Impala check engine light on question [Re: JimPghPA]
artificialist Offline


Registered: 09/23/07
Posts: 8535
Loc: Florida
I would sometimes encounter steel EGR lines that would crack during removal, so I say you just leave the EGR system alone until you have extra time. You can probably leave it alone for a while.
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