EGR P0401 Low Flow

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mpollice
Posts: 3
Joined: Sat Sep 06, 2014 5:21 pm

EGR P0401 Low Flow

Unread post by mpollice » Sat Sep 06, 2014 5:27 pm

2001 Impala 3.4L EGR valve was replaced. The code keeps recurring. Whats the next step?

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carriedi
Posts: 2280
Joined: Wed Apr 10, 2013 12:42 pm
Location: Oregon

Re: EGR P0401 Low Flow

Unread post by carriedi » Sun Sep 07, 2014 3:39 pm

low flow does not mean the egr valve isn't working. It means the MAP sensor did not read the intake vacuum change it was looking for when the egr was commanded on. Here's on reason that may cause this problem. The PCV system will allow oil to be drawn up into the intake very close to the egr port in the intake. That oil, over time, will mix with exhaust soot and plug up the egr passages.

(example: removing throttle body and EGR valve will provide access to both ends of passageway. Removing vacuum tee at the top of intake will allow a straight line of access for cleaning with a long screwdriver etc. The crooked passage over to EGR was cleaned with a piece of speedometer cable or something flexible.)

mpollice
Posts: 3
Joined: Sat Sep 06, 2014 5:21 pm

Re: EGR P0401 Low Flow

Unread post by mpollice » Wed Sep 10, 2014 5:20 am

thanks for the info. so I 'll check the map sensor and clean the intake at the specified locations. There's also a noticeable decline in fuel economy

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carriedi
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Location: Oregon

Re: EGR P0401 Low Flow

Unread post by carriedi » Wed Sep 10, 2014 10:06 am

if you drive with the check engine light on you may have a reduction in your mileage because you are driving when the computer is making up for a bad value.

mpollice
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Joined: Sat Sep 06, 2014 5:21 pm

Re: EGR P0401 Low Flow

Unread post by mpollice » Thu Oct 23, 2014 5:05 am

I had a dtc p0401 so I removed the throttle body and the egr valve . There was a large deposit of carbon blocking the passage, so I removed it. I then erased the dtc. the car runs great, gas mileage returning to normal. Is there anything else I should look for.

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carriedi
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Joined: Wed Apr 10, 2013 12:42 pm
Location: Oregon

Re: EGR P0401 Low Flow

Unread post by carriedi » Thu Oct 23, 2014 10:55 am

nope, that's it. that probably took care of your egr flow problem.

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