K, I have a friend with a 6th gen sedan ex 2.3 vtec. He has two oxygen sensors before his cat, one in the exhaust manifold collector and the second after the flex pipe and before the cat. The one on the manifold is heated and the one behind the flex pipe is not.

What is honda doing here? Usually they place a sensor before and after the cat to get a differential for the functionality of the cat. All that I can think of is the ecu pulls info from the heated one when the car is cold, then switching over to the unheated one when she's warmed up, but that really seems pointless.

Any ideas???

 

btw we are trying to install a SS header and downpipe, but its missing the bung for a O2 sensor in the header. There is one after the flex pipe.

We can cut and weld in another bung for the first O2, but we are wondering what the hell is the purpose for both of them before the cat.

 

the cars OBD 2 uses both of them to measure the air/fuel to adjust the map, and make the car efficient and emission skimpy.

sohc

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHCMAN &raquo;</TD></TR><TR><TD CLASS="quote">the cars OBD 2 uses both of them to measure the air/fuel to adjust the map, and make the car efficient and emission skimpy.

sohc</TD></TR></TABLE>

putting them after the cat dont help w/ air/fuel mix, cause the cat will burn up any gas not burned off during combustion........

 

the way I understand it is that the computer takes a differential across the cat to check to see if its running and the adjust the air/fuel ratio. But why does this car have just two before the cat. One is heated and the other is not.

 

maybe your friend is lying to you.

yes there's two o2 sensor, one is in the collector/downpipe and the other is in the middle of the cat.

 

I looked at the one in the exhaust manifold, right in the collector seen from the engine compartment and I saw on his downpipe the one right after the flex pipe. This is a EX 2000 Accord.

Someone mention it might be a temp sensor for what is hitting the cat...

 

you are correct, and yes, both are o2 sensors...i'm not exactly sure why honda did this on the accords...they did it on mine too when i had the factory exhaust and mine was a 96...i think your guess about the engine temperature might be fairly accurate though...

 

i agree i think also its something along egt style..

to help detech if the system is overheating.. as well as perhaps to allow the system to read emmisson based stuff