Hi Guys:
So I have a 2004 Honda Civic Coupe LX with 130K miles on it. My exhaust manifold was cracked so a friend of mine changed it and I also replaced both oxygen sensors. The exhaust manifold with Catalytic converter was a Dorman brand and the oxygen sensors were made by NTK. After driving for a few days with the new stuff I noticed my car struggling/hesitating while accelerating. The codes were P0135 and P0134. Upon further review, it seems like my upstream oxygen sensor NTK 24425 was only an oxygen sensor, but not an air-fuel oxygen sensor. So I got an upstream Denso 234-9005 air fuel ratio oxygen sensor and the hesitation is gone and the car runs smooth. However, the P0134 (bank 1 sensor 1, no activity) check engine light is still on. I cleared the engine light with the OBD2 scanner numerous times and still no luck. I replaced the ECM fuse under the hood and replaced the Air fuel relay fuse under the dash, but still no luck (all the fuses I replaced were working fine). After clearing the check engine light and starting the car the light comes on within 2 minutes. A friend of mine with help me do the continuity testing to see if there is no issue with the wiring, but I don't think that will be the issue.

I'm afraid it is the ECM/PCM.

I read here that there may be a PCM software update? (https://repairpal.com/pcm-software-u...ensor-code-346). Has anyone else done this?

Any help would be greatly appreciated since I have my Emissions test in a few months and I want to fix this problem. I searched online, but can't seem to find a solution to my problem. Thank you!

 

Are you sure that the catalytic converter isn't blown out?

 

I don't think the catalytic converter is the problem. I forget to add that since the catalytic converter and the exhaust manifold were together, when my friend changed the exhaust manifold, it was replaced with the Dorman 674-608 exhaust manifold with the catalytic converter.

 

No, you mentioned that... however, Dorman is a cheap part manufacturer and has been known to have issues from time-to-time with the quality of their products. I was just checking to see if it didn't arrive faulty, or fail early on.

 

It did not cross my mind that the catalytic converter could be the problem. I have the exhaust manifold w/catalytic converter installed for almost 2 months now and have not noticed any issues. Plus don't you think if the catalytic converter was problem I would get another code besides P0134? This P0134 code is driving me insane. Thanks!

 

put the old sensors back in and clear the codes and see if it goes away

 

I wish I had the old sensors. Being an idiot I threw them away thinking I will not need them.

 

How much was the manifold? Iam only asking because they are 800$ around here


I have never had luck with anything beside honda brand sensors

 

The manifold with catalytic converter was $275. The $800 seems quite high. I know California has stringent emissions standards so those may run around ~$400 or higher.
I may need to buy the original Honda oxygen sensor.

 

The factory manifold/catalytic converter lists for $658 from Honda. $800 is a little overpriced, but not extraordinarily high. You paid very little for yours, and it may be reflected in the quality of the product received.

 

seafoam it and look for white smoking leaking out somewhere

 

Thats retarded

 

Hey Guys so an update.
After having bad luck with the Denso oxygen sensor I was left with two choices: buy the original honda air fuel upstream oxygen sensor or replace the ecm/pcm. I decided to buy the honda oxygen sensor (part #: 36531-plm-306) and the check engine light never came on. I have now driven over 500 miles and no check engine light! Great success!

 

not at all