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C. Walker, Jr.
C. Walker, Jr. , Auto Mechanic
Category: Car
Satisfied Customers: 709
Experience:  Shop training and experience.
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Smart four two Diesel: My 2005 Smart car .8 3cyl. Diesel has

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My 2005 Smart car .8 3cyl. Diesel has only half the power it should. Some times it is ok and other times it is not. Code comes up as P0401 Exhaust gas recirculation flow insufficient detected. Dave S.
After you cleaned the EGR valve you should reset the battery by disconnecting it for five minutes. Check and see if the code comes back. You can also attempt driving it with the EGR valve off if it has better power with it removed this can be one of two things. The EGR valve is bad or you have a bad catalytic converter.

So first try resetting the check engine lamp. If the vehicle still runs rough the code may not come back right away but it will eventually. Try removing the EGR and drive it. If it seems a little better replace the egr if you still have the same issue the catalytic converter is plugged up.

Let me know if you have any questions, thank you
Customer: replied 2 years ago.

I would think that if the cat was plugged it would be act the same all the time, a plugged anything doe's not change. Dave S. Please comment.

What will happen is the honeycomb material will get damaged making the exhaust hard to push out. When it is cold it can still get through but after it starts warming up it will make the holes almost closed causing all the pressure to go back towards the front. So once hot it will run worse than cold.
Customer: replied 2 years ago.

My question is will replacing the EGR valve fix the performance problem. It is about 400.00 for an EGR valve plus labor. The car runs the same when it is cold.

Ok, replacing the egr valve would solve the problem if the valve is not functioning. The code suggests the EGR is failing. I would try removing the egr and running it without it. It should show a change in performance if the valve is sticking. This will verify replacement is needed.
Customer: replied 2 years ago.

After I cleaned the egr valve I drove it and it was at about half performance and I parked it at my shop. I cleared the codes with the scanner and ran it but the code came back, so I turned it off and had other stuff to do. I just took it for a ride after your last reply and took it for a good ride down the highway and it ran perfect with all its power. I am assuming from this that this would eliminate the cat after heating it up that much, is that fair to say or not. I am thinking it is an EGR valve that is working intermittent . Is that a good assumption or not. Dave S.

Yes, sounds to me like the egr is intermittently failing sticking closed.
Customer: replied 2 years ago.

You wouldn't happen to know where I could get a used EGR or a new one other than the dealer, the scrap yards don't seem to have any of these cars .

You will have to search hard. Since there are not a great deal of these out they do not have any aftermarket parts at this time. You can use or

I found 2 on ebay but they do not show the part number to verify if it is the correct part.

There is one out of the UK

Link here
C. Walker, Jr., Auto Mechanic
Category: Car
Satisfied Customers: 709
Experience: Shop training and experience.
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