Hey

Ok so I am a little puzzled. I have a 1991 4th gen prelude and recently got a 1997 BB6. What puzzles me is that both cars have what looks like a secondary oxygen sensor. Naturally the BB6 will have it being OBD2 but I cant see why the 4th gen has it, especially since its a 1991 (its from japan). The pics below show the two CAT's from the two cars, both with a sensor coming out of the CAT. The first picture is from the BB1 and the second pic is from the BB6.

Now what I need to know is if it will matter if I remove the CAT off the BB1 prelude. It has a wire running off to the ECU, I assume, so I am not sure if I can remove it without at a CEL.

 

that's prob the exhaust temperature warning sensor. it's a sensor in the cat that comes on when the temp of the cat is abnormally high. do u have a dummy light on the dash that looks like a cat converter with wavy lines above it? should be on the bottom row, left/middle?

 

Yea I do believe there is such a indicator light, its to the left of the low oil pressure indicator. So the BB6 has the secondary O2 sensor in stead of a temp sensor for the CAT? Makes sense. Any CEL codes when not plugged in? I may have to try it and see.

Strange, I cant find it in service manuals either (I have a USDM and EUDM service manuals).

 

It's a JDM only thing, you wont find it in USDM and EUDM manuals. There was a thread all about it a while back, pretty much lets you know when you have a clogged cat. Do a search on it and you might be able to find the thread, light came on, OP removed the cat and saw it was clogged, replaced cat and light went off.

 

it is actually covered in the '96 service manual under fuel and emmissions.

both of those pics look like the same sensor. the secondary O2 looks like it would go in the hole behind that (on the actual exhaust pipe) in the pics.

and it most likely will light up that dummy light if u remove it, but u could just pull the bulb.

 

^Wrong, 96+ are OBD2, his is a 91. You should look this up as well, the thread is here on H-T. He even said that the light with the cat symbol is on his dash where as you do not have that light on the dash.

 

i know '96+ are obd2, i have a '96.

i was just telling the OP where he could find info on it, that's exactly where i got it from. don't ask me why it's part of the '96 service manual, but it is. check for yourself.

i was just telling him where a secondary O2 would go if he had obd2.

 

Strange none of the 3 service manuals that I have mention the sensor. See the pic below (the EUDM manual didn't cover the H22A, H23A is the closest (had F20A4, F22A2&1 and H23A1&2)). Maybe you have a different manual, pic please?

I managed to take a photo of the light in the dash too. Check the bottom 2 photos.

I spent atleast an hour if not 2 going through old threads using different key words. Found lots of threads on the cat but not the one specified. Key words were "clogged cat", "catalytic converter", "cat light", "exhaust temperature", "exhaust sensor", to name a few. All searches were done in the prelude forum only. So I couldn't find it.

 

here it is: