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Old 03-21-2005, 12:28 PM   #1
doghouse
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Default P0031-->Front O2 Heater Questions

Hello. I have a '97 Outback into which I have transplanted a '02 WRX motor. I've got about 40k miles on the setup and only now have gotten around to hooking up the OBDII and reading the codes. I have several, some which I am aware of, and some which puzzle me. There was no fuel tank pressure, temp, or level sensor or fuel pump controller circuit in the Outback, so all those codes are present (any ideas how to "fake" those?). But the one that really puzzles me is the P0031 --> Front O2 Heater Circuit. I've checked all the wires going back to the ECU, checked for proper voltage and grounding of the circuit, and even tried three different O2 sensors. All to no avail. Any ideas? Thanks.
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Old 03-22-2005, 09:40 AM   #2
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Nobody even wants to take a stab at helping me on this one?
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Old 03-22-2005, 10:15 AM   #3
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Quote:
Nobody even wants to take a stab at helping me on this one?
Gimme a minute......






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Old 03-22-2005, 10:30 AM   #4
doghouse
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Thanks for that. Although I have already been through their whole procedure. Three times. And like I said I even used three different sensors. I'm just not sure what else to check at this point. Is it possible the ECU is bad? I mean of course anything is possible, but is it likely?
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Old 03-22-2005, 01:25 PM   #5
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...then there is something that is either non-functioning/mal-functioning or is an artifact of the swap that you have yet to uncover.

Is it possible that the wires for that particular function are reversed???

I remember reading that somewhere, that o2 sensor wires were reversed, one model to another.....but I don't recall details.
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Old 03-22-2005, 02:17 PM   #6
doghouse
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The harness and ECU and Sensor are all from the same car. The gold plated pins in the connector line up. I backpinned the "sensor" wires and they are fine. I have 12V on the heater power wire and I checked the (two) wires coming out of the ECU that ground the sensor. Oh yeah and I checked the *other* heater wire to the ecu and it is fine. Hmmmmmmmmm...
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Old 03-22-2005, 02:54 PM   #7
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Is the sensor that you are using the correct PN for the MY/type of ECU you are using????
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Old 03-23-2005, 03:30 PM   #8
doghouse
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The first one came with the car, so yes. Interestingly enough, it is withing the 10 Ohm spec the manual (and the above item you posted) suggests. As were all the other ones I tested. I doubt they were from the same model year, although perhaps one of them was as it had the same connector. Thanks.
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