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Old 09-09-2010, 05:49 AM   #1
shinji666
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Member#: 152450
Join Date: Jun 2007
Chapter/Region: VIC
Vehicle:
2001 Impreza 2.5RS
Blue

Default Best way to get rid of P0420 CEL?

I have a 2001 Impreza 2.5RS with borla replica and stock cat. P0420 CEL have been going on and off throughout the whole time to a point it's pissing me off.

What's the best way to get rid of it for my car year?

1) spacer (spark plug)
2) wrap borla header
3) reflash ecu and delete that code (does it work for 2001?)
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Old 09-09-2010, 09:03 AM   #2
Boxer4Dad
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Location: SE Michigan
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2005 Saabaru 2.5i
OBP, or Black

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I think #1 (on the rear sensor) will work for you. #2 might, or might not. #3 is not a cheap way to go, but would work for sure.

I have had this code for a couple of years now. No biggie, except I can't use my cruise control...
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Old 09-09-2010, 09:18 AM   #3
GEE-OTTO
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Quote:
Originally Posted by Boxer4Dad View Post
I think #1 (on the rear sensor) will work for you. #2 might, or might not. #3 is not a cheap way to go, but would work for sure.

I have had this code for a couple of years now. No biggie, except I can't use my cruise control...
The rear is next to being a dummy sensor and if you can live with it more power. I hate flashing lights the best way to rid the P0420 is to get a tuner to disable it by changing the value ranges it recognizes as "optimal" this is simple and wont take a lot of time and you can run your UEL or EL setups MIL free
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Old 09-11-2010, 01:31 AM   #4
williaty
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2005 2.5RS Wagon
Regal Blue Pearl

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He can't have the car tuned since it's a 2001.

The park plug anti-fouler trick will work just fine on a 2001 however.
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Old 09-11-2010, 01:12 PM   #5
eppoh
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95 Honda wagon 66 Belanca

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I did the anti- fouler trick on my wife's Toyota. We got tired of looking at the light after replace one of 3 cats and two O2 sensors. It put out the light, but the fuel mileage dropped 1to 2 mpg.
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Old 09-11-2010, 08:10 PM   #6
kero
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SRP

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I had a local tuner log into the ecu, edit the map and permanently remove the DTC P0420 code. For my 07 that is the only real option.

For your year, I'm not 100% if the others will work but took the guy 10 minutes and never had a problem again.

Wrapping your headers will not 100% solve the problem but will take away the sewing machine sound cause by the thin walled headers.
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Old 09-12-2010, 03:05 PM   #7
williaty
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He has a 2001. He cannot disable the DTC in the ECU. The only viable option is the spark plug anti-fouler.


For those of you with a 2005 or newer, you cannot use the spark plug anti-fouler, or any other mechanical or electrical tick. You MUST disable the DTC in the ECU via tuning.
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Old 09-12-2010, 03:17 PM   #8
RaineMan
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Wait... if he's got the stock cat why is he getting a code in the first place?
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Old 09-12-2010, 03:19 PM   #9
williaty
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Quote:
Originally Posted by RaineMan View Post
Wait... if he's got the stock cat why is he getting a code in the first place?
Cats wear out over time. The OP has a 2001, it's time. Additionally, headers can make the stock cats not function properly due to changes in temperature and flow rate.
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Old 09-12-2010, 03:24 PM   #10
RaineMan
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Quote:
Originally Posted by williaty View Post
Cats wear out over time. The OP has a 2001, it's time. Additionally, headers can make the stock cats not function properly due to changes in temperature and flow rate.
Then maybe it's time he replaced the cat instead of trying all these crazy work-arounds.
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Old 09-12-2010, 03:29 PM   #11
williaty
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Quote:
Originally Posted by RaineMan View Post
Then maybe it's time he replaced the cat instead of trying all these crazy work-arounds.
1) A spark plug anti-fouler is less than $10
2) A new cat pipe starts at $550 and goes up FAST.
3) He has aftermarket headers. Even healthy cats stand a large chance of not working.
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Old 09-15-2010, 06:05 PM   #12
kero
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My bad didn't realize OP had a 01
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