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Old 02-05-2004, 09:56 AM   #1
T33
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Default P0440, P0420 the CEL's that stay

A little lengthy but I hope someone here can assist.
The dealers are completely unable to assist, except for clearing the check engine light, but not solving the problem. I'm hoping someone here can shed a little light on the issue.
I have a 2003 WRX with 16k miles. It has a gutted stock uppipe and a Prodrive axle-back muffler. These parts have been on the car for 12k miles and it runs beautifully.
Last week I filled up with premium at the same gas station I always go to. No problems. That afternoon, about 50 miles after my fill-up, I was on the highway cruising at 65mph. The Check Engine light came on. Everything was running perfectly, but I still pulled over. Nothing was out of place. The following day I took it to the dealer and he pulled a P0440 and a P0560. He cleared the light and told me the problem came from the cold temps and a possible loosely tightened gas cap.
That same night I was on the highway again and the light came back. I cleared the light by resetting the ECU.
The next day the light cam on again on the highway.
This morning I took it back to the dealer and he pulled a P0420. Told me to just drive it around and to come back if the light comes back.
I have run the original fuel out to fumes and refilled with Sunoco 94 octane. The light is temp. off b/c I was just at the dealer, but I'm positive it'll come back once I get on the highway.
I know this is lengthy, but I haven't been able to get to the root, or even mildly understand why I'm having this problem.
Thanks to anyone that can shed some light on this. I'm at a loss.
Tarik
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Old 02-05-2004, 11:22 AM   #2
mick_the_ginge
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P0420 Catalyst System Efficiency Below Threshold

You are missing some cat's and the ecu cat efficiency test have caught you.

Their are many CEL eliminators on the market that should be abel to solve this issue. You basically have to fool the ecu to think that the cats are working just right by messing with the rear O2 signal.
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Old 02-05-2004, 11:27 AM   #3
GAS
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Default CEL P0420

The CEL came on about 500 miles ago on my 2002 Subaru Impreza with 61,000 miles. Similar situation- I was driving about
65 mph for about 10 minutes when the light came on. The outside temperature was about 12 to 25 degrees F that day. I
refilled with premium gas and retightened the gas cap. After a few trips it went off for a day and then came back on. The P0420 stood for "Catalyst Efficiency Below Threshold". I had installed Bosch platimun 4 spark plugs about 15,000 miles ago which, from reading other forums, have been known to cause a P0420 code. A bought some NGK plugs to replace the Bosch ones.
I'll reset the ECU as see what happens.
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Old 02-05-2004, 12:45 PM   #4
T33
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Does the uppipe resistor mod fix this, or do I have to play with the rear O2 sensor to trick the Cat sensors?
What's the best way to clear all this up? Which CEL eliminators do you suggest?
Thanks.
T.

Also, I think it's a little strange that after 12k miles of perfect running, it's all hitting me at once like this.
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Old 02-05-2004, 02:02 PM   #5
KGreb
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To fix the P0420 you need to look at the CEL fixes for the rear O2 sensor. The resistor for the up-pipe fixes a different CEL related to the EGT sensor.

The test in your ECU for catalyst efficiency usually triggers when you're cruising ~50-60mph for 10-15 minutes. Have you changed your commute or driving style recently?
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Old 02-05-2004, 02:11 PM   #6
T33
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Thanks man. I have not really changed my commute or driving style. It has been roughly the same since I got my car.
Driving on the highway is exactly what triggered the CEL. Can you suggest a CEL fix for this P0420 error?
Thank you,
T.
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Old 02-05-2004, 03:08 PM   #7
Prairie Dawg
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I did the mechanical mod. no CELs since.

quick. easy. reversible.
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Old 02-05-2004, 03:13 PM   #8
T33
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Can you please elaborate on the 'mechanical mod'?
I'll do it if it'll wipe these CEL's out.
Need more info on this mod. Thanks.
T.
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Old 02-05-2004, 03:46 PM   #9
Prairie Dawg
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PM'd ya...
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Old 02-06-2004, 07:53 AM   #10
Subahaulic
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I used the MIL eliminator from Pony Express (~$20). Problem solved.
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Old 02-10-2004, 01:42 PM   #11
T33
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Last question for you guys. Has anyone had a P0420, Inneficient Cat CEL come on for taking the uppipe cat out? Please let me know if you have/have not.
1. Doesn't the new WRX/STI have NO uppipe cat?
2. Isn't that cat for cold starts anyhow? (My CEL goes on/stays on after hitting the highway)

The uppipe cat is the only cat that's missing on my WRX.
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Old 02-10-2004, 02:10 PM   #12
Zola
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Quote:
Originally posted by T33
Last question for you guys. Has anyone had a P0420, Inneficient Cat CEL come on for taking the uppipe cat out?
You will not get P0420 from putting in a catless uppipe. P0546 is the code most associated with uppipe installs. It is a trivially easy fix. P0420 is typically from a catless downpipe. You can buy the Pony Express fix as posted earlier, or make your own with about $2 in parts from Radio Shack.

Quote:
1. Doesn't the new WRX/STI have NO uppipe cat?
Correct, the STi has a catless uppipe in stock form.

Joel
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Old 02-10-2004, 03:25 PM   #13
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Thanks for the info!
T.
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Old 02-11-2004, 09:44 AM   #14
T33
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I'm not sure why the dealer has been telling me P0440 when I found no evidence of such a code when I took the WRX to AutoZone and had them scan the car for free (great service btw). What they did pull was P0546-bingo! My uppipe EGT sensor is toast. Fine, easy fix.
The next code Autozone pulled was 1312. On a Porsche it's fuel injector #2 failure. But I can't find any other information on the 1312. Any insight on this one?
Thanks.
T.
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Old 02-11-2004, 10:21 AM   #15
mick_the_ginge
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P1312 Exhaust temperature sensor malfunction

http://home.earthlink.net/~opiewho1/...obd2_codes.htm

Watch this one, if I remember correctly it can put the ecu into limp mode. Replace the exhaust sensor with a 2.2 K resistor. With no cat in the uppipe your egt's will read above normal.
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Old 02-11-2004, 10:32 AM   #16
T33
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Thanks!
Am I running the risk of damaging things by driving with these issues? I've read it can be very bad for timing, etc.
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Old 02-11-2004, 10:38 AM   #17
mick_the_ginge
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Sorry, no idea about that one
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Old 02-13-2004, 12:27 AM   #18
ivrep
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I too got the PO546 code. And I did recently go catless in the up pipe. Did the 2.2k ohm resistor fix and haven't had any cel problems since. Get the 1/4 watt seems to fit better.
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Old 02-13-2004, 01:46 PM   #19
T33
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I have a question re. this fix.
Is there any long-term problems that could result from 'tricking' (ie-installing the resistor) the ECU and freely allowing higher temps to feed the turbo b/c there's no cat?
Just wondering if I'm going to have to start replacing things in a year or two.
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Old 02-13-2004, 01:52 PM   #20
Zola
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Typically removing the pre-cat in the uppipe actually lowers EGTs. Also consider that the STi comes from the factory with no pre-cat. I'm approaching one year with the resistor fix with ZERO issues, nor do I expect any.

Joel
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