p0401 for 2001 Toyota Camry

My car is a 2001 Camry with about 85K miles. About 4500 miles ago, the engine check light came on and shortly thereafter I changed the PCV valve using a toyota part. The engine light remained on. After driving on the new pcv valve, the engine check light went out and stayed out for about 4000 miles. Then it came back on. It stayed on for about 200 miles and then it went off again. Now it has returned. I went to Auto Zone who provides a free scan (very nice that they provide this as a free service) to extract the Powertrain code and it showed a p0401 which indicates that there is an EGR flow problem.

Not sure of the urgency to fix this problem and what is the downside if the repair is delayed. Can anyone help with this? Can any damage be created if this is not repaired right away. Car seems to be running fine. Does this have a negative effect on gas mileage?

I would also like help with the following questions:
1.) Can the problem be isolated by doing the job myself, or is this something quite involved that should be done by a technician?
2.) What is involved in doing the diagnostics and repair? Could a cleaning fix the problem? Can someone provide detailed steps that need to be done?
3.) Is it likely that an EGR valve or EGR vacuum modulator would need replacement with only 85K miles?

Thanks very much. I appreciate any help that anyone can provide.

The most common things that can cause this code on a toyota is the modulater valve and the vacuum switching valve. The modulator is located right next to the egr valve and the switching valve is under the intake, kinda difficult to get to. With the light going on and off like this I would lean more towards the switching valve because it will stick and then work again. But a good idea to change them both.

I would try a good cleaning before I did anything else. When I was at the dealership we would get alot of these in with the EGR valve and pipe full of carbon showing this code. Often, they would be so dirty that the valve wouldn't close on deceleration, causing a stall after a long drive on the highway.

If it was a carbon problem why would the light go off and on at will. If the ports are clogged then they are clogged untill cleaned. He was not complaining of a stall just the light being on at times. But I have run into many times what you are saying but this does not sound like what he is describing.

Since my original post, the light went out again and has been off for about 140 miles. Thanks for the replies. It seems from my readings on the forum that the vsv sticking problem is a pattern with Camry's. The other suggestion was carbon cleaning. I am not sure what is used to do the cleaning that is being suggested. I am also wondering whether the cold temperatures could also have a bearing on this problem. Now that the cold weather is settling in the east, perhaps it is not sticking as much. Just a wild guess. Any insights would be appreciated.

The one question that was not answered and I still would like to know is the urgency level with doing this repair. Does it have any adverse effects to the car if it was not repaired immediately?

Thanks again to those who have replied.

I wasn't so much talking about the ports being plugged solid as just having some build up which could cause the pintle of the EGR valve to get stuck periodically. I recall that the 4 cylinder 92-01 Camry usually responded well to cleaning. Personally, I think its always worth a try to see if cleaning something will resolve the problem before pouring money into it. My labor on my vehicle is always free!!