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P0420 Catalyst System Efficiency Below Threshold #4543988
10/15/17 11:02 AM
10/15/17 11:02 AM
Joined: Dec 2005
Posts: 10,328
Upper Midwest
kschachn Online content OP
kschachn  Online Content OP
Joined: Dec 2005
Posts: 10,328
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, 238K
1996 Honda Accord, 266K
1999 Toyota Sienna, 407K
2000 Toyota ECHO, 280K
Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn] #4543994
10/15/17 11:09 AM
10/15/17 11:09 AM
Joined: Dec 2008
Posts: 3,116
Occupied Virginia
Bottom_Feeder Offline
Bottom_Feeder  Offline
Joined: Dec 2008
Posts: 3,116
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!

Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn] #4543995
10/15/17 11:10 AM
10/15/17 11:10 AM
Joined: Oct 2012
Posts: 2,478
Staten Island, NY
michaelluscher Offline
michaelluscher  Offline
Joined: Oct 2012
Posts: 2,478
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
'01 Mercury Villager Estate VG33E 52k
'06 Ford Taurus SE Vulcan 60k
'13 Chrysler 300 3.6 Pentastar 230k
Re: P0420 Catalyst System Efficiency Below Threshold [Re: Bottom_Feeder] #4544009
10/15/17 11:21 AM
10/15/17 11:21 AM
Joined: Dec 2005
Posts: 10,328
Upper Midwest
kschachn Online content OP
kschachn  Online Content OP
Joined: Dec 2005
Posts: 10,328
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, 238K
1996 Honda Accord, 266K
1999 Toyota Sienna, 407K
2000 Toyota ECHO, 280K
Re: P0420 Catalyst System Efficiency Below Threshold [Re: michaelluscher] #4544010
10/15/17 11:22 AM
10/15/17 11:22 AM
Joined: Dec 2005
Posts: 10,328
Upper Midwest
kschachn Online content OP
kschachn  Online Content OP
Joined: Dec 2005
Posts: 10,328
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, 238K
1996 Honda Accord, 266K
1999 Toyota Sienna, 407K
2000 Toyota ECHO, 280K
Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn] #4544038
10/15/17 11:39 AM
10/15/17 11:39 AM
Joined: Aug 2008
Posts: 21,313
ON, Canada eh?
StevieC Online content
StevieC  Online Content
Joined: Aug 2008
Posts: 21,313
ON, Canada eh?
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?


'18 Dodge Grand Caravan GT - AMSOIL SS 5w20
'06 Santa Fe - 535,000km AMSOIL SS 0w30 / ATF
Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn] #4544039
10/15/17 11:40 AM
10/15/17 11:40 AM
Joined: Dec 2005
Posts: 10,328
Upper Midwest
kschachn Online content OP
kschachn  Online Content OP
Joined: Dec 2005
Posts: 10,328
Upper Midwest
So why is the fuel trim so high on sensor 2? What does that mean?


1994 BMW 530i, 238K
1996 Honda Accord, 266K
1999 Toyota Sienna, 407K
2000 Toyota ECHO, 280K
Re: P0420 Catalyst System Efficiency Below Threshold [Re: StevieC] #4544040
10/15/17 11:40 AM
10/15/17 11:40 AM
Joined: Dec 2005
Posts: 10,328
Upper Midwest
kschachn Online content OP
kschachn  Online Content OP
Joined: Dec 2005
Posts: 10,328
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, 238K
1996 Honda Accord, 266K
1999 Toyota Sienna, 407K
2000 Toyota ECHO, 280K
Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn] #4544041
10/15/17 11:40 AM
10/15/17 11:40 AM
Joined: Mar 2015
Posts: 5,426
Virginia
bbhero Offline
bbhero  Offline
Joined: Mar 2015
Posts: 5,426
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..


Nissan Altima 3.5 Coupe
Mobil Super 5w30 Wix 57356
"Treat your family like your friends and treat your friends like your family."
Re: P0420 Catalyst System Efficiency Below Threshold [Re: michaelluscher] #4544059
10/15/17 11:56 AM
10/15/17 11:56 AM
Joined: Nov 2012
Posts: 234
NorCal
Seventh Offline
Seventh  Offline
Joined: Nov 2012
Posts: 234
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.

Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn] #4544095
10/15/17 12:45 PM
10/15/17 12:45 PM
Joined: Dec 2005
Posts: 10,328
Upper Midwest
kschachn Online content OP
kschachn  Online Content OP
Joined: Dec 2005
Posts: 10,328
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, 238K
1996 Honda Accord, 266K
1999 Toyota Sienna, 407K
2000 Toyota ECHO, 280K
Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn] #4544102
10/15/17 12:50 PM
10/15/17 12:50 PM
Joined: Jan 2008
Posts: 10,972
OH
SatinSilver Offline
SatinSilver  Offline
Joined: Jan 2008
Posts: 10,972
OH

Re: P0420 Catalyst System Efficiency Below Threshold [Re: Seventh] #4544118
10/15/17 01:14 PM
10/15/17 01:14 PM
Joined: Apr 2012
Posts: 5,596
MA
Wolf359 Offline
Wolf359  Offline
Joined: Apr 2012
Posts: 5,596
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.

Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn] #4544131
10/15/17 01:27 PM
10/15/17 01:27 PM
Joined: Jul 2004
Posts: 12,071
Middlesex County CT
simple_gifts Offline
simple_gifts  Offline
Joined: Jul 2004
Posts: 12,071
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; 102K; ASL
2007 Yaris 78K 0w-40 Castrol
2006 B2300;132K;ALM


Was driving an ox cart; Now on the USS Enterprise
Re: P0420 Catalyst System Efficiency Below Threshold [Re: kschachn] #4544198
10/15/17 03:09 PM
10/15/17 03:09 PM
Joined: Nov 2004
Posts: 7,806
Texas
GMBoy Offline
GMBoy  Offline
Joined: Nov 2004
Posts: 7,806
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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