o2 sensor - Honda Prelude Forum

DNick · 05-15-2010, 08:51 PM

Hey, I swear I saw this on the site before, but I can't for the life of me find it now. I want to know how to check if my o2 senor is still fine. I have a CEL, code 67. And one of he things I've read, is that it could be a o2 sensor causing to go off. Anyways, I have a Helms downloaded on my computer, but I can't find out where it tells me how to check them.

Kronn 98SH · 05-15-2010, 09:27 PM

Quote:

Originally Posted by Kronn 98SH

67 - Catalyst System - P0420 (efficiency below threshold)

Step 7: Turn to Chapter 11, Pages 46-50. Find the code in the charts and turn to the page indicated. Begin troubleshooting.

^

FYI, 98% of the time, CEL 67 means bad cat.

DNick · 05-15-2010, 10:11 PM

Yeah, I know, was just wanting to check other things before I got it replaced.

Kronn 98SH · 05-15-2010, 11:22 PM

Well let me know how it goes.

indylude18 · 05-16-2010, 07:06 AM

Quote:

Originally Posted by DNick

I want to know how to check if my o2 senor is still fine. I have a CEL, code 67. And one of he things I've read, is that it could be a o2 sensor causing to go off.

Switch the front and back O2 sensors and see if the CEL code changes from cat to a primary O2 code. If it does, you need a new sensor. If it doesn't change, replace the cat.

DNick · 05-16-2010, 09:33 AM

Thanks, I'll try that. Which kind of brings me too my first question again. I'm very new to mechanical work, but I like to, and want to do it myself. I don't even know what o2 sensors look like, let alone where they are. SO, where are they? I look at the 5th gen faq, but it doesn't tell you how to change them.

Da_lude · 05-16-2010, 09:55 AM

Just jack up your car and look at your exhaust around the cat area, should be the only 2 sets of wires going into the exhaust. Hvnt had a stock exhaust for a long time but I think one is on the actual cat and the other is either just before or just after the flex pipe. Either way they are no more than a couple of feet apart from each other.
They can be a pain to get off though if they are rusted, so dont strip them lol

indylude18 · 05-16-2010, 02:54 PM

Both are welded to the cat, on right before and one right after. They look kind of like spark plugs from the outside and have a wire running in the end. You really can't miss them, there are the only sensors anywhere near the cat. To change them, just unscrew them with a wrench and unclip the wire harnesses. Should literally take 5 minutes.

DNick · 05-17-2010, 04:59 PM

Okay, sounds simple enough. After I switch them, should I reset by pulling the clock radio fuse. Or leave the CEL on.

indylude18 · 05-17-2010, 06:13 PM

Reset the ECU, then see if the code comes back. It probably will, which would mean you most likely need a new cat.

DNick · 05-17-2010, 06:22 PM

Alright. Sounds good, well not replacing the CAT, but the simplicity of ruling out the o2. Thanks so much for the help.

indylude18 · 05-17-2010, 06:26 PM

No problem. Report back with results.

Solid · 05-17-2010, 06:34 PM

Carsound/Magnaflow have some cheap cats if needed. Sparkplugs.com has really cheap O2 sensors.

You could also go with a test pipe and an anti-fouler for an even cheaper route.

indylude18 · 05-17-2010, 06:38 PM

oxygensensors123.com has OEM fit Denso O2 sensors for $35 with free shipping. Sparkplugs.com is a little more than that, or at least is was when I bought mine.