Rear o2 sensor options/simulators

[PollyPoger1]

Hi everyone,

I have a 2017 Subaru WRX that’s currently stage 2 with the Grimmspeed v1 j pipe. Car runs great and everything but because of the location of the car with the j pipe, it throws p0420 codes. I tried fixing this by using o2 sensor spacers, but that started throwing p0137 low voltage codes. I tried a few different sizes of spacers, and some get rid of the cel for quite some time, but they mostly come back when highway driving. I tried buying the magnum tuning o2 sensor simulator but that at the default setting throws p0137 still, and at the highest setting throws p0147 p0138 and another code (p2270 or something) saying stuck rich. I’m tuned by a local tuner in my area, and he’s disabled the comps from the rear o2 sensor so at this point it’s just check engine lights that I gotta worry about. Also, for some reason on the access port, the sns rear o2 volts only display shows that my o2 sensor with the spacer is outputting 0-3 volts which seems a little high. If someone has a stock j pipe and an accessport can chip in what kind of readings they get from sns rear o2 volts only, that’d be helpful too. At this point I’m either going to use the resistor and capacitor mechanical trick to try to get rid of it, or use a step down voltage generator to get around the same voltage going to the rear o2 sensor input to the ecu as a stock exhaust.

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[megagibby]

you ever figure this out? I tried 2 setups. 1 with 1 M ohm resistor and 1 uF cap, and also with a 4.7 uF cap.

with my tune and the rear o2 as is, im on the higher end around .7-.9 volts. With the 1M ohm resistor I was maxing at .22 v and eventually threw p0137. I feel that the 1M ohm resistor is too much and going to try a 330K ohm resistor next.

I was running some tests using an old O2 sensor and a heat gun. with no resistor and the heat gun about 1-2" away i was getting around 1v. same setup with the 330K resistor i was .5 - .7.

not sure if this would mess with the readings but another idea was to run the signal and ground cables into the inside of the car for easier swapping out resistors and caps for testing directly on the car.

[megagibby]

you ever figure this out? I tried 2 setups. 1 with 1 M ohm resistor and 1 uF cap, and also with a 4.7 uF cap.

with my tune and the rear o2 as is, im on the higher end around .7-.9 volts. With the 1M ohm resistor I was maxing at .22 v and eventually threw p0137. I feel that the 1M ohm resistor is too much and going to try a 330K ohm resistor next.

I was running some tests using an old O2 sensor and a heat gun. with no resistor and the heat gun about 1-2" away i was getting around 1v. same setup with the 330K resistor i was .5 - .7.

not sure if this would mess with the readings but another idea was to run the signal and ground cables into the inside of the car for easier swapping out resistors and caps for testing directly on the car.