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Discussion Starter · #1 ·
for a long while now the odb ii scanner has given me the Cat Efficiency Below Threshold error code.

the last time I had to pass California SMOG I reset the computer to clear the code and passed with flying colors.

I replaced both O2 sensors (the one on the side was easy, the one towards the back was next to impossible) and I still get this error.

i've searched the forums and i've seen the info on the v6 "recall" and some suggestions. but nothing seems to fit. I pass smog, and replacing the sensors didn't fix it.

I don't want to replace the cat, and I'd love to clear the CEL permanently.

thanks,

aran
'99 1.8T
 

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How many miles do you have on the car.

There is a 8 year 80,000 mile warranty on emissions related parts which includes that cats. Sounds like you could have a bad cat.
 

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Discussion Starter · #3 ·
I have about 130k miles on it right now, but i can't even guess when it started doing this because for more than a year I had the infamous ABS unit failure.

after I replaced the ABS module I was thrilled that my CEL would disappear... but it didn't so I checked and I had the 02 sensor issue. it's always something isn't it :)

thanks for the quick response!
 

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Did you check the main fuse for the ABS pump? It's way down under the dashboard. It's a big mother, too; it looks like a regular auto fuse with a gland problem.
 

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Discussion Starter · #6 ·
Purplezr2:
I'm using a borrowed odb ii scanner from Autozone, i'll stop by there tonight and check it out.

deusexaethera:
i'm assuming the ABS Pump fuse is on the drivers side under the dash? is it like a normal fuse where it's fairly obvious if it's blown? also, why would this bring up the CAT Below Threshold error code?
 

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Discussion Starter · #7 ·
ok ODB II Readout info:

P0422 Main Cat Below Threshold (Bank 1)

also lingering from my blown ICM module:
P0303 Cylinder 3 Misfire
P1239 Manufacturer Controlled Fuel and Air Metering.
but i just replaced the ICM today and cleared the codes tonight, so those two shouldn't come back ... like i said, always something :)
 

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Discussion Starter · #8 ·
sweet! lots of Search Results for "P0422" i'll post a link to anything that might be useful for me or anyone also interested
 

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Discussion Starter · #9 ·
so from reading the search results, would re-torqueing the o2 sensors be a possible solution? I'm pretty sure I torque'd it to spec, but who knows, it was tough to get at that back one.
 

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Maybe. If that doen't work, and you can't replace the CAT, you could try the spacer trick that CAT-less cars use (using a sparkplug anti-fouling spacer on the rear O2 sensor).
 

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same problem

I have a similar problem just got a reading P0421 and it said cat below treshold bank 1. Do I need to take care of this right away or can the light sit out for a while? I was told by mechanic that it won't harm my car but I may have a bad cat. This would only come into play if I had to get a smog.

I want to know if you were able to drive for a while with the emissions light on.

Thanks.
 

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Discussion Starter · #12 ·
misvits:
it's been on for about a year now... the only thing it might be harming is the environment, but i had it smogged in the last year and it passed with flying colors.

Rusty:
so what i would do is remove the o2 sensor, basically put a washer on it, then pop it back in? I'm guessing that would put it out of the way of the exhaust a smidgen, and that the air is nicer up there?

aran
 

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No, You need to get a spark plug anti-fouler,(some times you may need 2) drill it out with a 15mm drill bit and screw that into the o2 sensor bung. Then take you o2 sensor screw that into the anti-fouler and hook up the sensor then enjoy no engine light.
 

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PassatWorld Staff
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What he said. ^^^
Hopefully someone else can link to to exact directions, meanwhile when I get time I'll find a link for you. It's pretty easy.
 

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Discussion Starter · #15 ·
Thanks zzoomz and rusty!
after a quick search (now that i know the right keywords) i found a link to this thread on vwtortex which has some pretty detailed instructions:
http://forums.vwvortex.com/zerothread?id=1366095&page=1

one question: the CAT in the pictures (and probably the car) are not the same as mine. in my '99 1.8t the O2 sensors are on the left side of the engine and on the back side of the engine.

which one is Bank 1? and if it's the one on the back side of the engine, what is the easiest way of getting at it? it was pretty difficult to reach from above and just as difficult from below.

thanks!
aran
 

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If you have a 1.8t you only have one catalytic bank. You have two sensors: Bank 1, sensor 1 is before the catalytic converter and Bank 1, sensor 2 is behind the catalytic converter.
 

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Discussion Starter · #18 ·
Since the ODB II at Autozone only says "Bank 1" any thoughts on which sensor is more likely the culprit?

rear sensor would be my guess, but i'd much rather deal with the front one :)
 

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You need the diagnostic trouble code. OBDII will give you a PXXXX code. Go back to Autozone and get the code(s).

Just saw you had P0422 code. Your cat is probably bad. It's probably not 02 sensor. If you want to try to bung trick then it's sensor 2 the one behind the cat.
 

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Discussion Starter · #20 ·
thanks ken... that's what i was afraid of.

i guess i'm just not looking forward to the hefty price tag of a new cat install...

but what i really don't understand is why i am passing smog with flying colors if i have a failing cat. (but i already replaced the o2 sensors and that didn't fix it)
 
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