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Old 01-22-2004, 12:09 PM   #1
yebokmj
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Question P0420 Catalyst System Efficiency code help?

I am getting this code P0420 Catalyst System Efficiency Below Threshold (Bank 1) so I replaced the front O2 sensor only to get the same code thrown. I have had my kit for years never before coming across this problem. I have larger injectors and I am wondering if possibly it's to much fuel? But then wouldn't I get some sort of fuel trim code? Help?
Joshua
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Old 01-22-2004, 12:23 PM   #2
leondal
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Maybe the cats need to be replaced.....
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Old 01-22-2004, 12:35 PM   #3
lotusTT
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Actually the front O2 sensor doesn't have much to do with this (at least I don't think). The rear O2 sensor is the one that will throw this code. Its probably the cat going bad or the rear O2 sensor dying.
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Old 01-22-2004, 12:46 PM   #4
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the cat is dead
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Old 01-22-2004, 12:52 PM   #5
yebokmj
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Default Bank 1?

Bank 1 though is before any of the cats why would the cats be effecting anything?
Joshua
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Old 01-22-2004, 01:05 PM   #6
lotusTT
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Well this is the same CEL you get from running cat-less, I'm not sure what the Bank 1 part means though.
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Old 01-22-2004, 01:15 PM   #7
yebokmj
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Default Bank 1

I have two high flow cats. Bank one is the first O2 sensor. Bank 2 is the second O2 senor after the cats.
Joshua
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Old 01-22-2004, 01:21 PM   #8
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actually it's B1S1 and B1S2 which is B1S1=Primary B1s2=Secondary


P0420 is a bad cat, not a bad O2 sensor
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Old 01-22-2004, 01:45 PM   #9
Wedge
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If you have a custom (with a downpipe which replaced the stock cat), you will eventually get the P0420 CEL code. It is completely normal, does NOT mean your cat is going bad, just do an ECU reset, if the light annoys you. Or go standalone,
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Old 01-22-2004, 02:19 PM   #10
yebokmj
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Default I have cats

I have the JC Sports GB Kit, so I have two 2.5 High flow cats in my down pipe. I can understand why a bad cat or lack of cat would give such a code for Bank 2 but why bank 1? It's readings are before the cat.
Joshua
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Old 01-22-2004, 02:48 PM   #11
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no, there is no B2 on these cars, only B1....B2 woudl refer to a V6 with 4 O2 sensors
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Old 01-22-2004, 03:18 PM   #12
yebokmj
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Default I see

Okay I understand now. So is there a way to help clean my cats? Or are they not clogged but gone broken down over time. I do get a lot of popping and such. I don't have the money to get a new down pipe. I can alway break them out but I would prefer not to. Any suggestions would be apprecited.
Joshua
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Old 01-22-2004, 03:19 PM   #13
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there's nothing you can do except replace them, how many miles are on them?
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Old 01-22-2004, 03:22 PM   #14
yebokmj
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Default Hmm

Between the two cars it's been on I would say 40-50 thousand? I'm poor at record keeping
Joshua
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Old 01-22-2004, 03:25 PM   #15
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well REvision had the cats in his JC Sports Kit fall apart as well, you coudl try contacting PDM turbos who made the kits and see if he will do anything for ya.

Jeremy
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Old 01-22-2004, 08:40 PM   #16
Unsung Boxer
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HndaTch hit it right on the head.

Bank 2 is only on V formation cars where they run 2 primary 02 sensors.

Sensor 1 is primary
Sensor 2 is secondary
Cat inefficency is only seen by sensor 2

Check to see if the cat is toast by jacking up the car and smacking the catalyst. If you hear stuff rattling around in there, its trashed. If you see bits of catalyst in the tailpipe or muffler, it is junk.

Alot of times, its the sensor itself. Check by replacing the secondary sensor with your old primary one... it should work

They are both 3 wire 02 sensors.

-Jake
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Old 01-23-2004, 02:00 AM   #17
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hey yebokmj,
I have the same kit(bought it used)with the same problem as well but my secondary cat came hollow. You should be able to bring your downpipe to a local shop and have some new cats welded in instead of buying a whole new downpipe. I spoke to Joel Cox early last year about a new downpipe and he didn't seem very interested in making me another one.I think JC/PDM has gone through several redesigns on the pipes, whick makes it a hassle, but I could be wrong.
Rog
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Old 02-02-2004, 01:34 PM   #18
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I just got that checked out today since I got a CEL a week ago after putting a 2.5" catback exhaust...reset the ecu and went away momentarily and then it came back up.

P0420 code at autozone...is it time for turbo yet? LOL or will fuel injector cleaner work?

Kevin
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Old 02-02-2004, 05:33 PM   #19
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i yhave heard that the borla headers will cause this too. It seems like basically anything that alters the temp of the exhaust before it gets to the cat can cause this. With the borla headers I read in a thread here that thermal wrap fixed the code. Maybe wrapping your exhaust up to the cat will get teh cats hot enough to be effective?

you mentioned larger injectors.. what are you controlling them with? I know running too rish all the time will destroy a cat, and leaded gas might kll the o2 sensors..

If you do get a new o2 sensor, can I have your old one? My car came missing a sensor so I need to weld a bung in and would like to just splice a universal sensor in with the old clip instead of buying a new subaru one.
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Old 02-03-2004, 02:41 AM   #20
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IIRC, the P0420 is caused by aftermarket goodies( like the Borlas I have) and the code can be pulled but it may return(as in my case). The "best" step is to get this: http://www.ponyexpressperformance.co...liminator.html

After I double check the recent CEL, I'll have that done.
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Old 02-03-2004, 03:54 AM   #21
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P0420 is not usually cuased by a header, then again if the header is not heat wrapped or jey hot coated i could see this being possible, if the car is fairly stock it needs a catalyst section which is covered under a 8yr/80k warranty, and that's federally mandated/

Jeremy
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Old 02-03-2004, 11:39 AM   #22
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Quote:
Originally posted by HndaTch627
P0420 is not usually cuased by a header, then again if the header is not heat wrapped or jey hot coated i could see this being possible, if the car is fairly stock it needs a catalyst section which is covered under a 8yr/80k warranty, and that's federally mandated/

Jeremy
hmmm i put fuel injector cleaner, reset the ECU and we'll see how many miles until it CEL's again (if it does, crossing fingers)...

kevin
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Old 02-18-2004, 12:00 AM   #23
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Thanks hndatch, Ive been looking everywhere for an explanation of bank 1, sensor 2.

I just installed a turboback with a scoobysport p0420 fix and now Im getting a P0138 instead (O2 sensor circuit high voltage, bank 1, sensor 2). What could be causing this?

Ben
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Old 02-18-2004, 10:23 PM   #24
latinskllz
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i still haven't gotten a CEL again...I would say try Lucas Fuel Injector cleaner with 93 Octane and reset the ecu...
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Old 02-19-2004, 03:43 AM   #25
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Quote:
Originally posted by electricpork
Thanks hndatch, Ive been looking everywhere for an explanation of bank 1, sensor 2.

I just installed a turboback with a scoobysport p0420 fix and now Im getting a P0138 instead (O2 sensor circuit high voltage, bank 1, sensor 2). What could be causing this?

Ben
you crossed a wire when you installed the MIL eliminator
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