VtecLudeDude99

Hey everyone! This is my very first post on preludeonline.com and it wont be my last! I am very excited to be part of this forum, and hope to share knowledge with all of you.

As to my problem, I recently bought a 1999 Honda Prelude Base with 156K miles on it. I had it go through emissions test and it failed. The OBD II reader at the emissions place threw the following codes:

P0131 - Primary Sensor Low Voltage
P0132 - Primary Sensor High Voltage

Honda quoted me at $300 for both the primary and the secondary individually, in which resulted me in showing them the finger.

So I went to shucks... The guy said "Which one is malfunctioning? Here, you can borrow my OBD II reader and give it a shot and then come back to me". So I did. The OBD II reader that I borrowed from the shucks dude threw the following code:

P0401 - Exhaust gas re-circulation flow insufficient detected

I told this to the guy, and he started talking about how I have to replace my EGR valve, or take it out and try to clean it myself to have it last me for a bit more...

At this point, I am extremely confused. I can find a primary sensor for 50 bucks on "autoparts.com" type websites, not to mention the secondary one. EGR valves on the other hand apparently cost between 100-150.

Has anyone experienced a similar situation? Any advise?

Thanks a lot everyone in advance!!

Dog_of_War

OK man im going to try and help you here - *disclaimer: I am in now way an expert, and trust me, someone with the technical know how will read this and give you advice as well, what im suggesting just might work or might not

first if you haven't done so, save these bookmarks/download your helms manual

Another DIY ATTS, ABS, & CEL (Check Engine Light) DTC

helms -

SpoonerTuner.com - Free downloadable Honda Acura Factory Service Manuals by HELMS

and if you need to replace the sensors - $40

http://www.oxygensensor123.com/item....DENSO&weight=1

Ok with that out of the way here we go...
If your primary sensor is out and throwing codes i personally would take out my secondary sensor , replace it in the primary's slot and then get a non fouler and throw the 'old primary' in the non-fouler-ed secondary slot.

This of course wont help if your EGR valve is bad, but might just help..

As for your EGR read:

confirming egr port procedure

&

write up on cleaning the EGR ports - Preludepower.com
(halfway down the first page is something about a X# year/X# miles warranty - id call your local dealership and ask )
&
Search

good luck!

__________________

-Aaron

leftbrain99

Give us the mileage on the car. I doubt you need a new EGR, and it's real easy to clean the existing one, but a tad tricky to get to the bolts that hold it in. There are write-ups all over the place on this. But if your EGR is clogged, very likely the EGR port is also clogged and that is a longer process, but still very doable on your own if you want to save about $150 bucks or so. The EGR port cleaning procedure is also well-documented, and you only need about $2 in parts, plus a can or two of carb spray, and maybe a wire clothes hanger. And you have to drill out the old port plugs. The write-ups, and Helms, tell you to use a slide hammer to pull them, I drilled, inserted screws and carefully pried them out with the back of a hammer

I just did this myself, and I was shocked at how much carbon had built up. I was not getting O2 codes, though, but it wouldn't sruprise me if your primary O2 sensor was fouled. Don't get the Honda one. You can find quality ones for well under $100. If your code said "Primary O2 Sensor" then you already know which one might be failing. The primary one is pre-cat. Secondary is post-cat.

Good luck, just do some research and you can tackle all of this yourself.

VtecLudeDude99

Thanks a lot guys for all your help and wisdom! I got paid today, so I can go and afford the O2 sensors and the EGR valve. I have a weekend project

leftbrain99

Don't buy an EGR valve, though, until you take the one you have off and inspect it. As long as you can push the piston and see that it moves freely and closes securely, it's fine. You just need to scrape the holes in the bottom out and spray with carp cleaner. Buying a new valve is a waste unless the valve mechanism really is bad. And it's not likely to fix your insufficient EGR flow problem, either, because the ports are probably clogged, too. You need to pull those plugs and clean those ports. You just need to buy new port plugs from Honda, and a new EGR valve gasket.

Dog_of_War

Let us know how this plays out

__________________

-Aaron