Hello y'all,

New to the forum, but a long time Accord owner. I have a 1999 Accord EX V6. My car is throwing the P0401 and P0402 codes. I finally thought I had the right wrench to get the EGR valve off to clean it up and hopefully clear the codes and pass emissions. I sprayed both nuts with Liquid Wrench and let it soak. I am not sure how long I actually let it sit. I was using a 12mm box wrench and stripped the nut on the backside of the valve because of the awkward angle and inability to get a real solid set on the nut with the wrench. I also didn't let the engine completely cool (waited about 2 hours...) so the nut could have been soft? The problem with the EGR valve is that it is bulbous at the top, and I was not able to get my 12mm socket on there, even with an extension. I got the first nut off no problem, but now I feel I am hosed. I know they make rounded nut sockets, but I am not sure if I can get one of those onto this nut. Please help, I need to pass emissions and update my registration ASAP.

 

There is a different type of locking Vise-Grip that is better for trying to take that off when it is rounded; Vise Grip 4LW. Hard to find locally; but, a few hardware stores may stock them.



6-point wrenches and sockets have less chance of rounding vs. 12-point. You can also try a 6-point wrench on the rounded nut; sometimes, there is still enough on the nut for a 6-point to grip it.

The torque on the nut should be about 16 lb-ft.

 

My first car the mechanic had to remove the power steering pump to replace the thermostat!

 

P0401 is usually for the EGR port. You may want to clean that first, clear all the codes, then see what code(s) remain, if any. Plus you may be able to access that nut easier with a socket or vice grips.

You may be able to break that nut loose by hitting on the side with a center punch.

Here is a video for cleaning the EGR port.

 

I agree vise grips may be a better way to go.

The craftsman rounded nut sockets should also fit. Be sure to use the smallest socket you can jam or tap down on the nut to insure a good grip. A wobbly extension is handy to help.

good luck

 

I got it off. A customer let me borrow his 12mm deep socket and long extension. I would suggest this method to anyone who is going to clean/replace the EGR valve. I guess I didn't round the nut off too bad. I'm going to replace the valve because it looks beat up even after cleaning it. The plastic connector port is also chipped. There wasn't a whole lot to clean up after I took it off. I agree, I am going to have to take off the plenum. That looks like quite the job and was my biggest fear. I was quoted from shops ranging from a $100 diagnostic and $250 - 350 to take the manifold off and clean the ports. Sunday car work it is. Thanks for all the replies!

 

Good post guys, good reading and help.

 

My nut stripped. I tried 11 & 12 mm sockets, no good. I tried heat, a mechanic's concoction of transmission fluid & acetone, Easy Off (for 24 hours) PB Buster (or whatever it is,) WD-40, vice grips, a nut splitter (WAY too big!) And now I've been chiseling away because no one else was able to break the nut either. What's under that nut? If I hit the bolt with the chisel can the bolt be replaced & if so, how hard is that job? I'm at my wits end. I need a car!

Thank you in advance!

 

The stud that the nut is threaded onto can be replaced. The studs are on the water passage.

https://www.hondapartsnow.com/resour...A5524FA173953F

 

THANK YOU!!! I've been working on this stupid thing for a week! You're a work saver!