I note the invidia auspec dp has the o2 sensor before the cat whereas every other dp and the stock dp seem to be the other way around. Is there any problem with the sensor before the cat? Does this sensor affect afr and if so wouldnt this be thrown out as I would have thought there is a lot more o2 before the cat than after where i assume the ecu thinks its located?

Is this something the tuner can work around or is this problematic? All seems fine after my tune but I am just curious about whether there are any adverse impacts that might not have any obvious symptoms.

I was also wondering about this! it shouldnt be a big problem, I might run catless myself anyway

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Wannabe Boy Racer- WRX 09 Slim Sedan 268.6HP 376.0 NM @1.2 Bar

Much wow
many powerr
very siberu

Catless ftw

Looking more into this yea that's weird the Aus spec has o2 before cat at very end of the pipe and american version has the opposite maybe ask invidia email them ask why they opted for that design.


Edit- I sent an email as I was curious aswell

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Wannabe Boy Racer- WRX 09 Slim Sedan 268.6HP 376.0 NM @1.2 Bar

Much wow
many powerr
very siberu

Let me know what they tell you. I have also posted this question in nasioc.

Did you hear back from them yet?

I always thought that the front O2 sensor monitored afr and the back one monitored cat efficiency. Hence you normally turn off the rear O2 fault alarms.

It is strange that invidia put the cat at the end of the dump. I think that this is probably to reduce impact on spool.

Strangely no i have not !??? usually they respond straight away how did nasioc go?

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Wannabe Boy Racer- WRX 09 Slim Sedan 268.6HP 376.0 NM @1.2 Bar

Much wow
many powerr
very siberu

Nothing.

I am just curious even if it just measures o2 for cat efficiency does the ecu still change any parameters if it doesnt get the reading it thinks it should. I assume just turning off the fault code would not prevent this if it behaves in this way.

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I don't think it adjusts unless it turns on a CEL. Many of the guys running flex sensors use the input that usually takes the rear O2 voltage in order to feed alcohol content data to the ecu for adjusting or logging.