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#4543988 - 10/15/17 12:02 PM P0420 Catalyst System Efficiency Below Threshold
kschachn Offline


Registered: 12/26/05
Posts: 9395
Loc: Upper Midwest
I am getting this code on my ECHO with a check engine light. I've been trying to read up on how to use the diagnostic information I get from my OBDII scanner and I just really don't understand what I'm seeing. Below is a typical display for the fuel trims and voltages, I'm sure that isn't good but does it indicate a bad catalyst or something else? Do I need to take more readings? Any help or suggestions would be appreciated, thank you.
_________________________
1994 BMW 530i, 227K
1996 Honda Accord, 262K
1999 Toyota Sienna, 394K
2000 Toyota ECHO, 267K

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#4543994 - 10/15/17 12:09 PM Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn]
Bottom_Feeder Offline


Registered: 12/07/08
Posts: 3009
Loc: Occupied Virginia
Have you ever replaced the O2 sensors or cats in that 17 year old, 262k mile vehicle?

I'm all for actually diagnosing a problem first before throwing parts at something, but new O2 sensors certainly would not hurt!

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#4543995 - 10/15/17 12:10 PM Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn]
michaelluscher Offline


Registered: 10/07/12
Posts: 2420
Loc: Staten Island, NY
Looks like a textbook bad cat

Look how the sweep of B1S1 (upstream of converter) is matched by B1S2 (after converter)

This is showing that the convertor isn't doing it's job

Either replace the post cat sensor, and put a spacer on it, or prepare to buy a new converter

Have you been driving around with a misfire?

OTOH, at 262k, it just may be worn out and done with
_________________________
'06 Toyota Camry SE V6 3MZ-FE 100k
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#4544009 - 10/15/17 12:21 PM Re: P0420 Catalyst System Efficiency Below Threshold [Re: Bottom_Feeder]
kschachn Offline


Registered: 12/26/05
Posts: 9395
Loc: Upper Midwest
Yeah, I replaced the sensors when the code first appeared a few months back, and the check engine light went away for a while but now is back and it never leaves. There for a while it would disappear for a day or two but come back, now it stays on all the time.
_________________________
1994 BMW 530i, 227K
1996 Honda Accord, 262K
1999 Toyota Sienna, 394K
2000 Toyota ECHO, 267K

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#4544010 - 10/15/17 12:22 PM Re: P0420 Catalyst System Efficiency Below Threshold [Re: michaelluscher]
kschachn Offline


Registered: 12/26/05
Posts: 9395
Loc: Upper Midwest
Originally Posted By: michaelluscher
Have you been driving around with a misfire?

Not that I'm aware of, it seems to run fine. I would get some other code perhaps if that is the problem?
_________________________
1994 BMW 530i, 227K
1996 Honda Accord, 262K
1999 Toyota Sienna, 394K
2000 Toyota ECHO, 267K

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#4544038 - 10/15/17 12:39 PM Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn]
StevieC Offline


Registered: 08/21/08
Posts: 17116
Loc: Ontario, Canada
Originally Posted By: kschachn
Yeah, I replaced the sensors when the code first appeared a few months back, and the check engine light went away for a while but now is back and it never leaves. There for a while it would disappear for a day or two but come back, now it stays on all the time.


Did you use Denso Oxygen Sensors or some other after-market brand?
_________________________
'15 Dodge Journey - 90,000 KM's - SSO 5w20
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#4544039 - 10/15/17 12:40 PM Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn]
kschachn Offline


Registered: 12/26/05
Posts: 9395
Loc: Upper Midwest
So why is the fuel trim so high on sensor 2? What does that mean?
_________________________
1994 BMW 530i, 227K
1996 Honda Accord, 262K
1999 Toyota Sienna, 394K
2000 Toyota ECHO, 267K

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#4544040 - 10/15/17 12:40 PM Re: P0420 Catalyst System Efficiency Below Threshold [Re: StevieC]
kschachn Offline


Registered: 12/26/05
Posts: 9395
Loc: Upper Midwest
Originally Posted By: StevieC
Did you use Denso Oxygen Sensors or some other after-market brand?

They are Denso sensors.
_________________________
1994 BMW 530i, 227K
1996 Honda Accord, 262K
1999 Toyota Sienna, 394K
2000 Toyota ECHO, 267K

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#4544041 - 10/15/17 12:40 PM Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn]
bbhero Online   content


Registered: 03/20/15
Posts: 4625
Loc: Virginia
I would most likely yes. On my car there's a clearly different code for misfires. I agree with the one fella who says it definitely the cat. If your voltage was all over the place with the downstream 02 sensor then it would just be that. But the voltage on both upstream and downstream sensors is corellated very well. It is the catalytic converter that's bad..
_________________________
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"Treat your family like your friends and treat your friends like your family."

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#4544059 - 10/15/17 12:56 PM Re: P0420 Catalyst System Efficiency Below Threshold [Re: michaelluscher]
Seventh Offline


Registered: 11/11/12
Posts: 234
Loc: NorCal
Originally Posted By: michaelluscher
Looks like a textbook bad cat

Look how the sweep of B1S1 (upstream of converter) is matched by B1S2 (after converter)

This is showing that the convertor isn't doing it's job

Either replace the post cat sensor, and put a spacer on it, or prepare to buy a new converter

Have you been driving around with a misfire?

OTOH, at 262k, it just may be worn out and done with


+1 to all this

If they don't do tailpipe emissions testing on your car where you live I'd put a spacer in there and cross your fingers. Aftermarket cats are garbs and factory ones are expensive.

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#4544095 - 10/15/17 01:45 PM Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn]
kschachn Offline


Registered: 12/26/05
Posts: 9395
Loc: Upper Midwest
Thanks for everyone's help. No, they stopped tailpipe inspections here a while back and only do the diagnostic connector test. I'll do something, I have to pass that inspection soon.
_________________________
1994 BMW 530i, 227K
1996 Honda Accord, 262K
1999 Toyota Sienna, 394K
2000 Toyota ECHO, 267K

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#4544102 - 10/15/17 01:50 PM Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn]
SatinSilver Offline


Registered: 01/24/08
Posts: 10159
Loc: OH

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#4544118 - 10/15/17 02:14 PM Re: P0420 Catalyst System Efficiency Below Threshold [Re: Seventh]
Wolf359 Offline


Registered: 04/27/12
Posts: 4750
Loc: MA
Originally Posted By: Seventh
Originally Posted By: michaelluscher
Looks like a textbook bad cat

Look how the sweep of B1S1 (upstream of converter) is matched by B1S2 (after converter)

This is showing that the convertor isn't doing it's job

Either replace the post cat sensor, and put a spacer on it, or prepare to buy a new converter

Have you been driving around with a misfire?

OTOH, at 262k, it just may be worn out and done with


+1 to all this

If they don't do tailpipe emissions testing on your car where you live I'd put a spacer in there and cross your fingers. Aftermarket cats are garbs and factory ones are expensive.


Looks like rockauto sells an Eastern Catalytic for about $257. Has a 5 year/50k warranty. Not as good as factory which is typically an 8/80k, but with that kind of mileage, I'm not sure how much more he was expecting. It might even be time to call it quits as that car is probably only worth 1-2k.

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#4544131 - 10/15/17 02:27 PM Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn]
simple_gifts Offline


Registered: 07/26/04
Posts: 11945
Loc: Middlesex County CT
https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/4096510/Echo_Exhaust_Job.

Perhaps the recently posted thread about bypassing the photobucket issue will help.

Not a bad job to do with some air under the car and some serious extensions for the connection to the manifold.
_________________________
2004 Prius; 92K ML Syn 5W-30
2007 Yaris 68K 0w-40 Castrol
2006 B2300;130K;ALM


Was driving an ox cart; Now on the USS Enterprise

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#4544198 - 10/15/17 04:09 PM Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn]
GMBoy Offline


Registered: 11/22/04
Posts: 7702
Loc: Texas
Throw a spacer (spark plug anti-fouler) on that after cat oxygen sensor and problem fixed. Buy the deep ones and you usually don't have to drill them out. Double them up too.

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