My 2001 Accord 4 cyl VTEC with Auto trans and 182,000 miles has the two codes mentioned in the subject line. I put an aftermarket (not OEM) cat converter on about two years ago. The original one was rattling like a baby's toy. The CEL came on about 3 weeks ago and was intermittent for about a week but is now constant. I took the EGR off today and cleaned it and the two ports that feed to it (vacuumed the gunk out with a vacuum.) Does my model required the drilling I've seen to clean the other ports under the trottle body assembly? Will cleaning this also affect the P4020 code or do you think it will need a new cat also?

 

I would clean the EGR port running down the side of the intake manifold.

See this thread:

https://www.hondaaccordforum.com/for...r-valve-40569/

Once you clean the port, have the codes cleared, and see if any return.

 

If you're going to take the intake manifold out to clean the EGR port, might as well clean out the intake runner, they could get very gunked up inside. Look at the injectors before clean up http://imageshack.us/photo/my-images...accord085.jpg/ after http://imageshack.us/photo/my-images...accord087.jpg/
ImageShack Album - 4 images

 

Finally took off the intake cover and cleaned out all the gunk. Now the car is surging at idle. 1000 rpms up to 2000 then back down to 1000. I'm sure I got all the vacuum hoses back on properly. there are two plugs at the intake entrance, one blue and one gray. I put the blue one on the back and the gray one on top/front. I did lose a bit of antifreeze out of a couple of the hoses I had to disconnect. any ideas?

 

You probably have air in the cooling system.

When the engine is cold, remove the radiator cap. Then open up the bleeder valve on the thermostat housing to allow air to escape. You need a 12mm deep socket. Close that valve when a steady stream of coolant comes out (air stops spitting out of there). Top off the radiator with coolant. Run the car with the radiator cap off.


Search Youtube for zUpXgAJ1gjU

It is a video describing how to do this.

 

I did as the youtube video described. Everything went as expected--but I still have idle surge at 1000 to 2000 rpms repeatedly. At 2500 rpms I had no idle surge and the cooling fans came on and went off. I saw no large bubbles from the radiator but lots of tiny,tiny ones. I opened the bleeder valve as described. I set the interior thermostat setting to high. Do I need to let it idle longer, do I need to turn on the interior blower? Your suggestions are greatly appreciated.

 

Since you took off the manifold, maybe you have a vacuum leak. Google this: 9CPqbaSgcok its a video on finding a vacuum leak.

There should be a sticker under your hood showing how the vacuum hoses are routed. I know older accords had those stickers. You want to make sure you connected the vacuum hoses properly.

 

One other suggestion I forgot about is to disconnect the battery for a few minutes to reset the ECU.

 

I know I got the three vacuum tubes on top of the entrance to the intake placed correctly because I took a before picture. I'll check out the vaccum leak info you provided. I did disconnect the battery but I uplugged the gray electrical plug on top of the entrance to the intake while the car was running and that cause the CEL to come back on (the surge did go away it seemed though) . I'm going to try an ECU reset again before I do anything else.

 

Your surging is more than likely coming from the IAC valve, I ran into this same thing the last time I had mine off to clean it. The two coolant hoses you took off run to the IAC. Take the IAC back off and clean it up really good, then put it back on and spray some intake cleaner through the engine, and then reset the ECU. That should do the trick!