Code P0420-Catalyst Efficiency Below Threshhold Bank 1

kaplan3jiim.RemoveThis@example.com writes:

> Got the subject code for check engine light pulled at Auto Zone.
> Car is a '97 Subaru with 165,000 miles.
>
> Could this be the catalytic converter? Auto Zone person said it could
> be 0xygen sensor. How does on ascertain what the actual problem is?
> Is the O2 sensor easily accessible on the 2.2l engine?


Amazingly, last week I got this same code on my 01 2.5L.

My cat is new as of about 10 months ago. O2 sensor is new too, I
believe.

I reset the code with my odb-ii scanner, and drove 600 miles and it
hasn't returned. I'm holding my breath and hoping at least.

--
Todd H.
2001 Legacy Outback Wagon, 2.5L H-4
Chicago, Illinois USA
 >> Stay informed about: Code P0420-Catalyst Efficiency Below Threshhold Bank 1 

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 >> Stay informed about: Code P0420-Catalyst Efficiency Below Threshhold Bank 1 

On Mon, 23 Jun 2008 23:20:53 GMT, dk.RemoveThis@no.email.thankstospam.net (DK)
wrote:

>In article <g4lv54tlj2g6aak9getlihagcp3hfc0nqi.RemoveThis@4ax.com>, kaplan3jiim.RemoveThis@example.com wrote:
>>Got the subject code for check engine light pulled at Auto Zone.
>>Car is a '97 Subaru with 165,000 miles.
>>
>>Could this be the catalytic converter? Auto Zone person said it could
>>be 0xygen sensor. How does on ascertain what the actual problem is?
>
>The Subaru procedure step by step:
>
>1. Check if there are other codes (P0130, P0133, P0136,P0139, P0037,
>P0301,P0302, P0303, P0304,P1130, P1131, P0031,P0032 and P0038?
>If yes, investigate those and disregard P0420. If not:
>
>2. Check exhaust system
>Check for gas leaks or air suction caused by
>loose or dislocated nuts and bolts, and open
>hole at exhaust pipes.
>NOTE:
>Check the following positions.
>- Between cylinder head and front exhaust
>pipe
> - Between front exhaust pipe and front catalytic
>converter
> - Between front catalytic converter and rear
>catalytic converter
>If no problems:
>
>3. CHECK REAR CATALYTIC CONVERTER.
>Separate rear catalytic converter from rear
>exhaust pipe. Any damage? If not:
>
>4. CHECK FRONT CATALYTIC CONVERTER.
>Remove front catalytic converter.
>Any damage? If not:
>
>5. Contact Subaru distributor
>
>So unless you have issue elsewhere, things point to a
>catalytic converter...
>
>DK

Thanks. Will probably put this on hold unil closer to next June when
emissions inspection is due again. I seem to recall catalytic
converters are quite expensive but one online site has each of them
for under $200. Does that not include the platinum stuff?

Jim
 >> Stay informed about: Code P0420-Catalyst Efficiency Below Threshhold Bank 1 

<kaplan3jiim DeleteThis @example.com> wrote in message
news:34j0645t21474vdouhudaeb5jgqgs12pi5@4ax.com...
> On Mon, 23 Jun 2008 23:20:53 GMT, dk DeleteThis @no.email.thankstospam.net (DK)
> wrote:
>
> Thanks. Will probably put this on hold unil closer to next June when
> emissions inspection is due again. I seem to recall catalytic
> converters are quite expensive but one online site has each of them
> for under $200. Does that not include the platinum stuff?
>
> Jim

Aftermarket cats are not a direct fit, they need to be welded to your pipes.
Also they typically don't hold up very well. I would encourage you bite the
bullet and get your cat(s) from the dealer.
 >> Stay informed about: Code P0420-Catalyst Efficiency Below Threshhold Bank 1 

On Jun 23, 12:57 pm, kaplan3j... RemoveThis @example.com wrote:
> Got the subject code for check engine light pulled at Auto Zone.  
> Car is a '97 Subaru with 165,000 miles.  
>
> Could this be the catalytic converter?  Auto Zone person said it could
> be 0xygen sensor.  How does on ascertain what the actual problem is?
> Is the O2 sensor easily accessible on the 2.2l engine?
>
> TIA
> Jim

My son's car has the same code. I did a little research via Google and
am going to replace the O2 sensors - they seem to be the culprit at
least 50% of the time, according to what I've read on-line. Typically,
when a cat 'goes', it breaks up inside and you would get (at least)
some rattling and (at worst) a degredation in performance and/or gas
mileage as the loose material blocks the flow through the cat. My
son's car has neither symptom.

Dan D
'99 Impreza 2.5 RS
Central NJ USA
 >> Stay informed about: Code P0420-Catalyst Efficiency Below Threshhold Bank 1 

>My son's car has the same code.

I have very same code on my 2000 Mazda Protege ES

having a hard tine figuring out what it is. Mechanics
keeps saying the cat con..... but I'm weary abt that
and suspect O2 sensors
 >> Stay informed about: Code P0420-Catalyst Efficiency Below Threshhold Bank 1 

Dave wrote:
>
>
> <kaplan3jiim.RemoveThis@example.com> wrote in message
> news:34j0645t21474vdouhudaeb5jgqgs12pi5@4ax.com...
>> On Mon, 23 Jun 2008 23:20:53 GMT, dk.RemoveThis@no.email.thankstospam.net (DK)
>> wrote:
>>
>> Thanks. Will probably put this on hold unil closer to next June when
>> emissions inspection is due again. I seem to recall catalytic
>> converters are quite expensive but one online site has each of them
>> for under $200. Does that not include the platinum stuff?
>>
>> Jim
>
> Aftermarket cats are not a direct fit, they need to be welded to your
> pipes. Also they typically don't hold up very well. I would encourage
> you bite the bullet and get your cat(s) from the dealer.
Hi,
Certain gas brand works better for certain engine.
Here in Canada, I try to avoid Esso brand.
 >> Stay informed about: Code P0420-Catalyst Efficiency Below Threshhold Bank 1 

<me DeleteThis @privacy.net> wrote in message
news:f8a264dqjf8njjl3e6ph1vicf7dplo6jdt@4ax.com...
>
>>My son's car has the same code.
>
> I have very same code on my 2000 Mazda Protege ES
>
> having a hard tine figuring out what it is. Mechanics
> keeps saying the cat con..... but I'm weary abt that
> and suspect O2 sensors

The PO420 code sets when the correlation between the front and rear O2
sensors indicates the cat isn't doing it's job. If one of those two O2
sensors were actually bad instead, it would set a completely different code
and not the PO420 code.

If your car has more than 120k miles, it wouldn't hurt to replace the O2
sensors. You're going to need them sooner than later anyway. But after
clearing the codes you can bet the PO420 code will soon return leading you
to replace the cat(s) too.

And yes, I am a mechanic. Not just playing one on the internet.
 >> Stay informed about: Code P0420-Catalyst Efficiency Below Threshhold Bank 1 

Dano58 wrote:
> On Jun 23, 12:57 pm, kaplan3j....TakeThisOut@example.com wrote:
>> Got the subject code for check engine light pulled at Auto Zone.
>> Car is a '97 Subaru with 165,000 miles.
>>
>> Could this be the catalytic converter? Auto Zone person said it could
>> be 0xygen sensor. How does on ascertain what the actual problem is?
>> Is the O2 sensor easily accessible on the 2.2l engine?
>>
>> TIA
>> Jim
>
> My son's car has the same code. I did a little research via Google and
> am going to replace the O2 sensors - they seem to be the culprit at
> least 50% of the time, according to what I've read on-line. Typically,
> when a cat 'goes', it breaks up inside and you would get (at least)
> some rattling and (at worst) a degredation in performance and/or gas
> mileage as the loose material blocks the flow through the cat. My
> son's car has neither symptom.
>
> Dan D
> '99 Impreza 2.5 RS
> Central NJ USA
Hi,
Some OBD II scan software can anlyze O2 sensor performance reading the
output voltage. Around 2000, there was bad batch of O2 sensors covered
by warranty. Believe there is a TSB for this. My kids' 2000 Impreza O2
sensors were replaced during scheduled visit to dealer.
 >> Stay informed about: Code P0420-Catalyst Efficiency Below Threshhold Bank 1 

"Dave" <mecdave.DeleteThis@hotmail.com> wrote:

>The PO420 code sets when the correlation between the front and rear O2
>sensors indicates the cat isn't doing it's job. If one of those two O2
>sensors were actually bad instead, it would set a completely different code
>and not the PO420 code.
>
>If your car has more than 120k miles, it wouldn't hurt to replace the O2
>sensors. You're going to need them sooner than later anyway. But after
>clearing the codes you can bet the PO420 code will soon return leading you
>to replace the cat(s) too.

Ok thanks so much Dave!

I didn't realize al this

Sounds like it is in fact the cat con!
 >> Stay informed about: Code P0420-Catalyst Efficiency Below Threshhold Bank 1 

So the formal diagnosis is right side has failed and left side is on
the edge. All the bolts upstream are tight as new and no leaks.

OEM replacement cost including $300 labor is quoted as $1700 for the
pair.

Any other options that are worth doing? If I was sure nothing else
major (like engine or transmission) would crop up in the next 2-3
years it would be a worthwhile investment I suppose but has anyone had
any experience with aftermarket or rebuilt ones - which the shop is
trying to price as I write this?

TIA

Jim



On Mon, 23 Jun 2008 11:57:23 -0500, kaplan3jiim.DeleteThis@example.com wrote:

>Got the subject code for check engine light pulled at Auto Zone.
>Car is a '97 Subaru with 165,000 miles.
>
>Could this be the catalytic converter? Auto Zone person said it could
>be 0xygen sensor. How does on ascertain what the actual problem is?
>Is the O2 sensor easily accessible on the 2.2l engine?
>
>TIA
>Jim
 >> Stay informed about: Code P0420-Catalyst Efficiency Below Threshhold Bank 1 

kaplan3jiim RemoveThis @example.com wrote:

>So the formal diagnosis is right side has failed and left side is on
>the edge. All the bolts upstream are tight as new and no leaks.

Is it the cat con?

Or O2 sensors?
 >> Stay informed about: Code P0420-Catalyst Efficiency Below Threshhold Bank 1 

On Tue, 01 Jul 2008 11:23:11 -0500, me DeleteThis @privacy.net wrote:

>kaplan3jiim@example.com wrote:
>
>>So the formal diagnosis is right side has failed and left side is on
>>the edge. All the bolts upstream are tight as new and no leaks.
>
>Is it the cat con?
>
>Or O2 sensors?

No its the cat con(s). O2 sensors are good.

Was first quoted $1400 plus, for parts, for OEM replacement, but now
after checking around it's half that. Still a bit more than a grand
installed. Does that sound reasonable?
 >> Stay informed about: Code P0420-Catalyst Efficiency Below Threshhold Bank 1