As of yesterday all 4 of these codes popped up. My gas mileage is poor and when I reset the light, it comes back in 30ish miles. I placed my assumed fixes based on my findings from the search below, but is there a chance that something else could warrant all these codes? 180k

P0171 & P0174
I must replace the e.g.r valve and all 6 injectors. I may also need the PCM update from the dealer.

P0430 & P0420
The worst case scenario would be two catalytic converters and all 4 o2 sensors.

I did find a post in which an owner stated the first two codes came from a clogged breather hose that came from the transfer case. Is anyone familiar with that?

 

Have you checked your battery?

 

My battery is good. As an added measure, I cleaned the terminals.

 

seems like maintenance at almost 200k

Do you run premium fuel?

 

Yeah I do. I even went the full tank + sea foam route yesterday. Reset the light and 30 miles later CEL was back.

 

Pull off your EGR valve and give it a good cleaning with carb cleaner along with the EGR pipe that goes to the intake manifold.

From what we have seen here, P04#0 codes mean new cats are on the way.

 

I was afraid of having to get cats. I pulled the egr valve and the manifold off. They were both black so I carb cleaned them and still the CEL came back.

I found someone selling cats from an 08 TL. I recall reading that they fit so I'll have to pick up those.

 

I don't think those fit if they are from the J32. You need the 3.5L cats from the Accord or TL-S.

 

just get the high flow cats from RV6 #becuaseracecar

 

Sorry, I failed to specify that it is a TL-S. Really, the accord had a 3.5? Never knew that one.


Depending on the price, I just might. But then I'll need to fab up defowler

 

The Odyssey, Pilot, and Vue do too.

http://en.wikipedia.org/wiki/Honda_J_engine#J35

 

I got rid of that egr code just by changing really badly dirty air cleaner.
That might effect also to that cat thing if the engine doesnt get enough air.

 

That's where i intended to start. Hopefully a new filter and EGR valve will allow me to hold off on getting the injectors.

 

A new egr got rid of the p0171 & p0174 codes. The other codes remain so my dreams were killed. My quest for cats continue as the local ones have been sold.

 

your EGR got rid of Lean errors? that might be good news for me since I have 0401/0404 (egr) plus 0174/0171 (lean)
did you replace or lean or both?

 

I was getting the p0430 code too. I ran some seafoam though the power brake pump vacuum. It got ride of the code. My car has over 200 thousand miles. No more codes.

 

I replaced the egr valve and cleaned the port as well as the intake manifold. No more code after that.

 

I replaced both downstream sensors and that got rid of the 0430 and 0420 codes.