po420 code - Subaru Outback - Subaru Outback Forums

SubaruOutback.org is the premier Subaru Outback Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Rate Thread
Old 01-27-2007, 07:19 PM   #1 (permalink)
Registered User
 
Join Date: Nov 2006
Location: S.E. Connecticut
Car: 2001 Outback Wagon 2.5L
Posts: 122
Feedback Score: 0 reviews
Default po420 code

My trials with Subaru are not over... I just bought the car with 101K on it and since then I replaced the front O2 sensor and then it turns out I had an coolant external leak. They sent the heads off to be machined & the shop discovered valve guides in both heads had broken free. End result is I needed two rebuilt heads. $2,400 later and 1,400 miles down the road and when I started the car today I see a check engine light & a po420 engine code was identified at Auto Zone.

My searching says it's a bad catalytic or a pressure leak. I hear nothing like sucking air, the exhaust is not louder, the engine idles beautifully. I know the front O2 was replaced with an OEM 1,500 miles ago.

Coupla questions; How do I reset the CEL?

Any suggestions what to do first & then what to do second? I'm currently in the midwest & no junk yard around here has any Subaru anything & Auto Zone does not sell a cat for my OBW.

Thanks
__________________
2005 H6 silver Bean. 74K miles
Megalomando is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 01-27-2007, 08:09 PM   #2 (permalink)
IDK....my BFF Jill.......
 
ivwarrior's Avatar
 
Join Date: Nov 2005
Location: Lewistown, PA
Car: 2002 WRX MBP
Posts: 1,104
Feedback Score: 0 reviews
Default

Go back to AutoZone and get them to clear the code this time? That, or unhook your battery for about an hour should do it.

Recommendations? Get the code cleared and wait to see if it comes back.

If it does? Well, since the rear O2 sensor is what monitors the cat efficiency, I'd start by replacing that sensor, clearing the code again, and waiting to see if the light comes back or not.
__________________
One
Big
Ass
Mistake
America
ivwarrior is offline   Reply With Quote Quick reply to this message
Old 01-28-2007, 03:57 AM   #3 (permalink)
Registered User
 
Join Date: Nov 2006
Location: S.E. Connecticut
Car: 2001 Outback Wagon 2.5L
Posts: 122
Feedback Score: 0 reviews
Default

Hey there iv,

I asked him to but he said they weren't clearing codes anymore. I went to another place & they read the same code & gave me a printout saying:

DTC (codes)

P0420
Catalyst Efficiency
Below Threshold
(Bank 1)


DTC Pending (Codes)

P0420
Catalyst Efficiency
Below Threshold
(Bank 1)

This 2nd place was willing to help me do the clearing but he didn't want to do it & gave me the scanner & had me do it myself. Said they did it up till 6 mos ang & were told to stop. Also said that from 1996 on unplugging the battery would not clear as it did in years before.

Regardless, that did clear the codes & apparently reset the computer. The light's off now and I'll see if it comes back on. I ought to just get a rear sensor and put it on. I did the first as prevention.

I wouldn't mind just leaving the CEL on & forgetting about it but if something else comes up unexpectedly, I want to know about it when it happens.

Just looked at the price of Catylitics and they're higher than two completely rebuilt heads... Think I ought to find one from a junk yard if it comes to that...
__________________
2005 H6 silver Bean. 74K miles
Megalomando is offline   Reply With Quote Quick reply to this message
Old 01-28-2007, 01:08 PM   #4 (permalink)
Superb Moderator

 
bheinz57's Avatar
 
Join Date: Jan 2004
Location: Neenah, WI
Car: MY12 WRX, MY07 FXT
Posts: 6,188
Feedback Score: 0 reviews
Default

That's your second (rear) O2 sensor giving you that CEL. Normally due to an exhaust issue. The cats could be the issue, or the sensor could be failing. When aftermarket exhaust is used, you can get that code. I have had that code many, many times.

The local parts store can clear the code after they read it, but it may just come back on if there is still an issue.

Cold temps outside, a problem with the cats or exhaust, those can set the CEL on/off on it's own.

Brian
__________________
If you can't see into the future, you aren't driving fast enough
bheinz57 is offline   Reply With Quote Quick reply to this message
Old 01-28-2007, 02:47 PM   #5 (permalink)
Registered User
 
Join Date: Nov 2006
Location: S.E. Connecticut
Car: 2001 Outback Wagon 2.5L
Posts: 122
Feedback Score: 0 reviews
Default

Hi bheinz,

I'm in Indiana at the moment and the temps were around 18F when the light first came on so perhaps the cold was a factor.

I can order one of the rear sensors & try to replace that here although I don't have a lot of tools available. After spending so many thousands on problems with the car, I hate to pay for more labor costs... After buying this car less than two months ago I've put almost 4 grand into it and still there's problems coming up. It gets frustrating to say the least. I could have bought a much newer car with far lower miles on it for what I now have in this one but my crystal ball was foggy...

Ah well, at least the piston slap goes away after it warm up.

Thanks for the helpful reply, I truly do appreciate it!
__________________
2005 H6 silver Bean. 74K miles
Megalomando is offline   Reply With Quote Quick reply to this message
Old 02-25-2007, 12:32 PM   #6 (permalink)
Registered User
 
Join Date: Nov 2006
Location: S.E. Connecticut
Car: 2001 Outback Wagon 2.5L
Posts: 122
Feedback Score: 0 reviews
Default

In the assumption it's my cat that's been giving me the CEL (I've had it turned off 4 times now & it's back on within 40 miles or less every time).

I've considered just gutting the cat & replacing the shell back on the car & wit till my next test to see if it passes that way or not. My guess is it will probably not pass though the engine does seem to run well cept for the piston slap which 99.9% goes away (I can always seem to hear the tiniest bit of click in the engine other than lifter but I hear it because I'm looking for it. Once the engine is truly warm the obvious tick disappears)

I've also considered getting a high flow converter and having that welded in-line It looks though as if there's two catalytics on the same pipe and if I drive my car to a muffler shop bringing with me only one cat, I doubt they would just weld that one cat into the line, they'd want to add another.


Is it two catalytics between the sensors or just one & a resonator?


I looked at this cat & thought about bringing it to a shop to weld in a new ilne: Random cat

I also looked at this one which seems to use two of the random cats & is pretty much "plug & play" cept you need to lengthen the rear O2 wire 12"
Extreme cat

Lastly here's different cats for a 2001 2.5 OBW: Different random cats

OK... so another question is if I have just one of these cats built into a mating pipe would that be OK or do I need two of them to be OK & lastly, will this affect my noise level much if I still have the stock exhaust? It's kinda over the top to make a stock station wagon sound like it has balls specially the way I drive.

What I would want would be better MPG & an exhaust that will pass emissions.

Decisions, decisions...
__________________
2005 H6 silver Bean. 74K miles
Megalomando is offline   Reply With Quote Quick reply to this message
Old 03-03-2007, 07:46 PM   #7 (permalink)
Recruit
 
Join Date: Oct 2004
Location: Houston, Tx
Car: 2000 Outback 2.5L 4 banger
Posts: 24
Feedback Score: 0 reviews
Default

I got aPO420 code this year and last. When the nighttime temperature was below 40 degrees, the light came on. Now that it's warming up, and we average over 50 at night, the light is off. From what I've read, it's most likely the rear O2 sensor.
Sensitive little bugger. For those who live in cold climates, the light must be on 6-7 months of the year
Bradford in Heavenly Houston
treeman is offline   Reply With Quote Quick reply to this message
Old 04-27-2007, 01:42 AM   #8 (permalink)
Recruit
 
Join Date: Apr 2007
Location: Western Maryland
Car: 2002 Outback 2.5L 135K Miles
Posts: 3
Feedback Score: 0 reviews
Default

I bought a 2002 2.5L w/135k on it and got the P0420 code also. I started with the Cat and the O2 sensors (figured that would definately take care of code) but it did not. After that, I replaced both front exhaust seals as they were both very brittle during the cat installation. That didnt work. Tried everything mentioned on these forums, better gas, new battery etc. After beating my head against the wall, I removed the entire exhaust and ripped off the heat shield on the down pipe (y-pipe before the cat) and found a really large hairline fracture. I was really surprised that I didnt hear it. Replaced y-pipe and fixed error code. Bought the Cat for $300 at BMA autoparts. A lot cheaper than dealer. Y-pipe is a dealer only item. I also purchased a code reader from autozone. $85 smacks. Pretty nice.

Not sure what i was thinking when I bought this car. After really taking a closer look I also found that the rear main bearing is leaking oil along with a slight head gasket leak. I also have a lot of oil around three of the spark plug boots. Everything that I am fixing has been mentioned here in these forums (at least I am not alone). I wish I would have joined before buying car. I have already replaced the timing belt, oil pump seals, front bearing seal, front / rear brakes and rotors and am thinking that the shocks will need replaced soon. I guess I cant complain since the car is five years old.
wolfmanjack is offline   Reply With Quote Quick reply to this message
Old 02-14-2014, 04:03 PM   #9 (permalink)
Registered User
 
Join Date: Jan 2013
Posts: 4
Feedback Score: 0 reviews
Default PO420 Code - 08 Outback Base Model

I think I had this post in the wrong place before, sorry, I'm new to the forum. Bought an 08 Outback with 27,000 miles on it and salvage title (no warranty) and got the P0240 code immediately. Had the dealer check it out multiple times. Cat checks out fine, replaced upstream and downstream sensors. Still get the code every 3-4 days no matter what the outside temp is. I would just drive it with CEL on but it disables the cruise control which is not an option for me. I bought a code reader so I could clear it myself - but this is getting old.

Replaced the battery - tried good gas, Sea Foam, no luck.

This air or exhaust leak is interesting though - that can be causing the code also? Any other ideas?

Note that the car took a right front corner collision (hence, the salvage title) which is where the exhaust, cat and sensors are so I thought for sure it would be one of those three things, but I was never looking for a cracked pipe before.
Rpedal is offline   Reply With Quote Quick reply to this message
Old 02-14-2014, 09:01 PM   #10 (permalink)
Super Moderator
 
cardoc's Avatar
 
Join Date: Aug 2012
Location: Austin, Texas
Car: 2001 VDC/SC One of a Kind
Posts: 10,420
Feedback Score: 2 reviews
Default

Quote:
Originally Posted by Rpedal View Post
I think I had this post in the wrong place before, sorry, I'm new to the forum. Bought an 08 Outback with 27,000 miles on it and salvage title (no warranty) and got the P0240 code immediately. Had the dealer check it out multiple times. Cat checks out fine, replaced upstream and downstream sensors. Still get the code every 3-4 days no matter what the outside temp is. I would just drive it with CEL on but it disables the cruise control which is not an option for me. I bought a code reader so I could clear it myself - but this is getting old.

Replaced the battery - tried good gas, Sea Foam, no luck.

This air or exhaust leak is interesting though - that can be causing the code also? Any other ideas?

Note that the car took a right front corner collision (hence, the salvage title) which is where the exhaust, cat and sensors are so I thought for sure it would be one of those three things, but I was never looking for a cracked pipe before.
Simple solutions to often misdiagnosed issues: P0420 Diagnosis
__________________
Sleeper VDC
P0420 Diagnosis

cardoc is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply


Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Subaru Outback - Subaru Outback Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 01:44 PM.



Powered by vBulletin®
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.3.2
Copyright 2009-2010 SubaruOutback.org. All Rights Reserved.