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Old 09-09-2012, 02:40 AM   #1
spoolinsti05
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Chapter/Region: Tri-State
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2005 TickingTimeBomb
Jr tuned TT Sleeved

Default po139 because UR downpipe?

Still getting this po139 would the semi o2 fix built into the ultimate racing down pipe cause the code?

or is it just because my tunes off? still waiting on my re tune.

the sensor voltage does seem to respond slow until it's fully warmed up. about .8v at idle then if i rev it up it will go to .7v once car's warmed up. short fuel trim's are still off and bounce from -6 to -15 to -25 back and forth.
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Last edited by spoolinsti05; 09-09-2012 at 02:49 AM.
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Old 09-09-2012, 02:54 AM   #2
teiva-boy
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A tune will 100% fix it. The mechanical cel fixes In some cases are just Band-Aids.
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Old 09-09-2012, 09:52 AM   #3
drewvdw
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Isn't the code P0420 for a malfunctioning catalytic converter? I don't know what that code is for.
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Old 09-09-2012, 12:23 PM   #4
mod maniac
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I think the 05 and newer uses the rear 02 to make fueling adjustments and it should not have a mechanical fix. The causes for this code could be a exhaust leak, wiring, bad cat, and others. You need to talk to a tuner and see what they can do.
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Old 09-09-2012, 02:06 PM   #5
spoolinsti05
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Jr tuned TT Sleeved

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Quote:
Originally Posted by mod maniac View Post
I think the 05 and newer uses the rear 02 to make fueling adjustments and it should not have a mechanical fix. The causes for this code could be a exhaust leak, wiring, bad cat, and others. You need to talk to a tuner and see what they can do.
It's an 05 sti with an 04 sti ecu for now putting my 05 ecu in when i go back for the re tune. po139 is o2 sensor 2 slow response.

The ultimate racing down pipe has a spacer/scavenging pipe welded type bung so i was wondering if that was causing the slow response as it seem's pretty logic. o2 sensor out of the flow will show this code correct me if i'm wrong. I have no leaks possibly a dieing o2. 46k miles on this one and it's seen race gas pretty sure.

will negative fuel trims cause the po139?

Last edited by spoolinsti05; 09-09-2012 at 06:45 PM.
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Old 10-06-2012, 12:37 PM   #6
spoolinsti05
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Well got it re tuned worked most the gremlins out. But still evap and o2 systems won't get ready.

Looking at my rear o2 voltage it does respond slow opposed to the front. also don't have the evap solenoid installed.

In NY your only allowed 1 system not ready. IDK what to do. I'd hope installing the evap solenoid and maybe a new o2 sensor will fix it. but no codes after 600 miles an still not ready.
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