P0420 - Catalytic Converter and 02 Sensors - Honda Accord

Hi..

I have a 1998 honda accord V6. I got the Check engine light today,
using an OBD scanner i found out the code was "P0420 - Catalytic
emission low on Bank #1". The local repair shop tell me that i need to
get the Catalytic convertor and the 02 sensors replaced.

I have the following questions for the group.
1. Does the code P0420 mean that the catalytic convertor is bad?
2. He quoted the cost for a replacement Catalytic convertor for $550
and O2 sensor for $138.. do these seem high?

Just a few days back i had replaced the alternator in this car .. FYI..

Thanks,
Ritesh

 

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"Catalyst system efficiency below threshold" is the interpretation. Your
second O2 sensor says that the CAT isn't scrubbing enough stuff from the
exhaust. It MIGHT just be the second O2 sensor's fault. (have you ever
had 'poor starting' after sitting overnight / weekend?) Maybe you've
never cleaned your injectors and so you've got a damaged CAT on that
side. Maybe you've used too many additives and have a damaged CAT. More
likely the former.

If it was mine, I'd do a tune -up, reset the code, put a can of techron
into a full tank and drive it until it was almost empty, preferably on a
long, fast highway drive on a hot day. The prices quoted are good to
low, as long as the O2 sensor is a real NGK. If it's Bosch, tell him to
get you a REAL sensor. Was he going to replace the first or second
sensor, BTW.??

'Curly'

 

Thanks curly,

I have never had poor starting problems with my car.. after a weekend
sitting idle...he was planning to replace the second sensor.. according
to what i have understood..

thanks for your help... i think i shall go ahead with the replacement..


ritesh

 

it just needs a cat, no o2 sensor.
Chip

 

id replace the O2 sensor, but NOT the cat. cats just dont go bad that
quickly unless youre using gas from questionable sources. for $138 it
sounds like theyre using a generic sensor. an OEM one would be closer to
$200 for the sensor alone.

 

Majestic prices out to $99 for the sensor (plus shipping and handling).
That would probably be NGK. Yeah, the prices are otherwise good. Did he
say the brand of cat it was? A DEC?

Do get a tuneup. Cat's don't go bad by themselves, something else cause
them to go bad.

As far as Bosch goes, they are fine sensors and they are the most
installed sensors on the road. NGK and Denso only make sensors under
Bosch licenses.

 

wrote in

There have been reports of this being caused by a cracked exhaust manifold.
The crack is just below the primary oxygen sensor, and allows air in AFTER
the sensor, which the primary sensor cannot detect.

Check for that before needlessly replacing the cat.

 

They are not Honda OEM, though, and anecdotal reports here
indicate they are a roll of the dice compared to OEM.

What does this mean? That a Denso O2 sensor is identical to
a Bosch O2 sensor, for the same car model and year?

I don't think so.

Another online parts resource for the OP:
https://www.automedicsupply.com/

About $70 for the upstream O2 sensor (OEM, Denso).
Another $70 for the downstream O2 sensor (OEM, Denso).

 

accord cats go bad all the time in from 98 to 02. It's very common
after 80,000 miles.
Chip

 

Did you know that American Honda has recently agreed to warranty certain
cats for 14 years and 150,000 miles? This exceeds the Federally mandated
8/80 warranty.

 

I have a 1998 EX V6 coupe and just installed the Honda OEM fog lights.
They work fine but I have some questions/observations:

1) They only operate when the headlights are turned on...not with the
parking lights alone or no lights...headlights MUST be on.

2) They continue to stay on when switching to high beams. Never
noticed this on other cars. Always seemed that fog lights cut out for
high beam operation.

Is all of this normal? Thanks.

KL

 

thats kinda crappy. how about the civic cats?

 

good luck actually finding a dealer willing to admit it, and do the work
though.

 

The information comes from the February issue of an auto restoration
magazine called "Skinned Knuckles" (page 10, middle of right-hand column).

The author of the article in question is Bill Cannon, an engineer who has
been intimately involved with catalytic converter design, development and
regulatory environment since 1953.

Fianlly, on a re-reading of the article I discover that I was not quite
complete in my citation: It seems American Honda will only warrant
emissions equipment for 14 years/150K on certain California models only.
The rest are covered under the standard EPA-dictated 8/80 warranty.

 

My catalyst was replace at 79,xxx on a 02 Civic Si under warranty. I sort
of contributed it to a spirited driving style wiht lots of neato
downshifting probably pulling oil past the rings and gumming up my cat.
I've adjusted my driving style and am now consuming a quart of oil every 5k
miles instead of 3k so I anticipate it will last longer.

 

ritesh--I also have a 1998 accord v-6. My alternator went out and the
next day I had a check engine light. It was the catalytic convertor and
cost me $1042.00 at the dealer in maplewood.

 

Dang... Proud of those suckers ain't they... I just had a new cat
installed on my 89 accord yesterday, and it cost me $159.00
installed.
Yep, I slightly flunked the emission test the other day...
I passed all but the high speed NOx... The guy that did the test
guessed I probably needed a new cat. I checked my EGR operation,
and at first thought it didn't work, but then found out the car had to
be moving.. It was working ok once I tested it driving.. Timing was
on the money. The mixture was set, and all vacuum leaks that I could
find were fixed. So... I decided to throw a new cat on it to squeak me
through. I'll take the retest tommorow. Should pass I think. I might
even slightly retard my timing just to be on the safe side..
I'd probably be lucky to sell my whole car for $1042.00.. Thats
just plain robbery when you consider the actual cost of a cat..
IE: a generic is about 50-60 bucks.. A direct fit replacement is a bit
over $100.. No telling what honda gets if you just walk in and buy
one..
I'm sure it's not for the faint of heart, or the light of wallet.
MK