Hey guys I just installed dc headers and greddy evo cat-back in my 97 accord lx. It is so tight. Sounds great and gave me a big noticeable amount of power. I had to customize the catalytic converter a bit to make it work. I cut the flange off on the header side and welded the catalytic converter to the down pipe of the header. While I was doing all of this I figured since I live in NY and emissions laws are not that strict I would gut the converter. Ever since the check engine light has been on. I removed the battery neg numerous times to try and correct it, but it just comes back on. I was reading an old thread and it said that on a 97 Prelude and installation of a Random Technology Cat Back, they were complaining about being too free flowing and causing the O2 sensor(s) to trip the check engine light with the P0420 code. It will pass emissions fine; however, your check engine light will always be on which can eventually cause other problems because the computer will be trying to compensate for the problem.
I think this is the same problem I have.
If anyone can give me any suggestions that would be awesome.
Otherwise I guess the only way around it is to take the whole thing back down cut the weld buy a new converter, modify that without gutting it and reassemble everything. My other option is to somehow disable or trick the secondary O2 sensor on the converter so it won’t trip the light. There was a thread about this at Honda- Acura's forum, but it was hard to understand their instructions. Has anyone ever had this problem and know how to bypass the sensor? Also is this ok to do? If I do this will the sensor still work?



So I went to AutoZone today. The code I got was PO141
Heater Circuit Malfunction Bank 1 Sensor 2. I guess that is the secondary o2 sensor on the converter. I’m going to try and disconnect it today and see what happens. If anyone has any insight on this problem please let me know?


Alright, so I disconnected the 2nd 02 sensor and then reset the ecu. Started the engine 5 seconds later the check engine light came back on. I'm really at a loss and do not know what else to do. I could really use some help.

 

Great question man. I wish i could help ya, but i`m having the same problem with the check engine light on my 99 accord, just got back from Auto Zone and got exactlly the same code as you did ( PO141- 02sensor, bank 1) So if anyone out there could help i would appreciate, and also does the sensor need to be replaced or what, if not replaced will it make other problems, etc.
THANX A LOT GUYS !!!

 

The computer monitors 02 sensor connection, so if you disconnect it, the light will go on. It also monitors voltage variance. Although, if it complains of heater circuit, you can bypass it by cutting the two same color wires and connecting them.

 

There is a device you can get that either plugs into the O2 sensor or taps into the wiring that fools the ECU into thinking the sensor is reading within specs. I forget who makes it, but if you do a Google search, you may find it. Try typing "O2 eliminator", or Oxygen Sensor Eliminator." My friend has one on his RSX Type-S, the Comptech Race header has no provision for a cat, much less an O2 sensor, but like I said, I forget who makes it. Good Luck.

 

I had to do the same thing on high flow converter install. Did it break your heart having to cut the DC flange off? My Cel light went off giving me a PO420, can't figure out how to turn it off.

 

the second sensor in you cat monitors its efficiency. if you gut the cat, or remove the sensor, you're going to get a cel. you need to get one of those 02 sensor simulators to replicate the voltage of the o2 sensor to get rid of the cel

 

now someone tells me! No one really responded to my Code 67 thread. Anyways this info comes to late for me. First I brought a new converter two days ago assuming this was what I needed to do. Second I went to Autozone today because they said they could erase the code. I got all excited because it worked and I thought I could just get my money back on the converter. One hour later the CEL comes back on . So I just went to a local auto shop so that they could install the converter. They install the converter and disconnect the neg battery terminal.

No more CEL!

Converter + install = $161
No more CEL priceless!

It's funny that I got a new converter and install for less than what I would have paid for 1 new sensor out here. The Bosch sensor ran for $184 at Autozone.

 

If you really want to keep the gutted cat on there then try buying a new sensor. If the code is the heater circuit it might not have anything to do with the converter. But gutting the cat won't really increase your power in most cases. In fact in sometimes can rob you of power because the larger chamber inside a hollow cat will slow the exhaust gas exiting the engine down and can actually create backpressure. It's not a big deal on F/I engines since they are pumping out so much exhaust so fast, but on N/A engines gutting the cat is pretty much worthless.

 

Ditto. If you want the CEL to go out, put a normal cat back on with an O2 sensor on it. You destroyed one of the biggest parts of our emissions controls, and are now wondering why the CEL(which monitors emissions controls also) was set off? Thats like asking why my tire is flat after I shoved a knife into it.

Also as far as NY laws are concerned and their strictness towards emissions, if you run a car with a gutted, or removed cat, they can confiscate your car, and you wont pass emissions testing with a CEL unless you have some connections.

Getting trick sensors, etc for what was in the end a pretty worthless mod which should have been more thoroughly researched first.

 

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when u initially installed the dc header did the cel turned on? I am thinking of getting one for my 01...

thanks