Oxygen Sensor Code and Cold Weather

Our 2005 Prius in Colorado Springs with 53,000 miles had a new experience 2 days ago: cold soaked overnight at -20 deg F temps, then driven at -10 degrees temps. Got a check engine light after 2 miles (no other lights) with P0137 DTC (bank 1, sensor 2 oxygen sensor). A 2008 post gave a great description of this code (below).
My question is: could this possibly be a false reading due to frigid temps, or just coincidence that the sensor failed on this bone-chilling day? Should I try a reset and see if it comes back? Car is out of warranty and dealer wants $350 to replace the sensor.

Thanks

Jim

Originally Posted by bnllovesme (2008)
The check engine light came on yesterday morning but I wasn't having any problems with the car. I took it in this morning and when they ran the diagnostics it came up with the P0137 code. Since I was under warranty they replaced it quick and I was out the door in an hour. After some time on google it looks like it's an O2 Sensor? Does this mean my catalytic converter might go next?
This code's description is 'Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2)'. This is the post-converter sensor, which confirms that the catalyst did its job. A low voltage indicates that the O2 sensor is reporting that there is a lot of oxygen in the exhaust. The computer thinks the voltage being reported is so low as to be a bad reading - that in fact it represents an open circuit (not connected).

Generally this code means that the sensor itself has failed, electrically. It doesn't have anything to do with the actual functioning of the catalytic converter.

If the code is repeatedly posted with a new sensor, it could indicate a hole in the catalyst letting in fresh air. Generally, though, the car would log P0420 (Catalyst System Efficiency Below Threshold) rather than this code.