Mazda MPV - minivan

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Ok my girls cousin is having some problems with her van her cel is P0037 I've looked over the net and come to the conclusion that it is an o2 sensor problem (low voltage, bad sensor etc etc) but I cannot find the location of this sensor. The van has 4 o2 sensors and I cannot figure out where the o2 sensor in question is, here is the code:

P0037- Bank 1 Sensor 2 Heater Circuit Low

If anyone could provide me help it would be greatly appreciated.

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Nvm I have figured out the Bank 1 sensor 2 location