Quote:
Originally Posted by Wepeel
I replaced with an aftermarket Bosch, seems to work fine. It definitely sounds like you're on your way to open loop. Peculiar but it seems there are a few of us that are seeing the same behavior.
I was wondering why it would have failed too. I'm only at 32k miles and never hit or banged the sensor - I did swap it in a few times since I went through 3 leaky borla header warranty replacements before I finally got the OFH, although I never even had to apply that much torque to swap the O2 sensor. Since there is no cat it's getting hit with hotter/dirtier air, so maybe that does have something to do with it. Although if it was that I'd think we'd start seeing more failures from everyone who's running a catless header (or maybe they're just not monitoring AFR constantly). I guess time will tell how much longer the new O2 sensor lasts.
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Thanks for the info. To add details to the discussion for future reference, I have only moved my O2 sensors once, when I installed my OFH over a year ago. They are definitely not cross-threaded, nor did I hit the sensors against the bung during install. I'm currently at 42k miles, with about 20k miles on the OFH. I monitor my trims pretty regularly and haven't noticed the commanded AFR dropping before the ~1.5 hour mark of constant RPM cruising on the highway. I regularly take 5-hour constant RPM trips, so perhaps if others aren't doing this, they would never notice the problem. Still not really sure how to mechanically/physically explain the timing, though (e.g. why it takes upwards of 90 minutes to see an effect).
I never saw this cAFR drop prior to installing the uncatted header (I ran OFT Stage 1 maps for about 12k miles prior to installing the OFH). Good to know that other uncatted headers seems to be causing the same issue.