P CODES (POWERTRAIN) P0100 - P0199 P0137

I'm Having A Heck Of A Time Finding Out If This Is Upstream Or Downstream, And Where I've Had Several Parts Stores Give Me Opposite...

Had Bank 1 Sensor 2 (high), Changed Rear 02 Sensor, Ran For Two Three Days, Coded The 441 And 137. Cleared Them, Ran Two Days Reappeared...

Po102, Po121, Po137, Po154, Po155, Po171, Po174, Po300, Po440, Po507.

So Today My Car Had The Same Issue Code P0137. I Had Changed The 02 Sensor Yesterday An Car Ran Fine. After Driving The Car For 6 Hours The...

The Mil Is Not On. Car Gets Lousy Gas Mileage (20-mpg At Best) Which Implies The Pcm May Be Operating On An Open Loop Circuit. I Put A...