P2237 code after topping off AC freon

I had an ac issue with my 2009 white prius where the air did not come out of the vents cold enough. I opened a thread here on priuschat and received many helpful comments.

AC starts off warm but gradually gets colder after several minutes of driving | PriusChat

so, i then topped off the freon in my prius and the ac was working as it should - nice and cold. I went home and turned off the prius.

the issue:
later i took the prius for a drive and shortly into the ride i saw the CEL. i used my OBDII reader and it was a P2237. wt !?!?!?!?

I have researched the P2237 and do not see how it can be related to topping off the freon. but, it started on the first new ride after topping off the freon. so, it is either a major coincidence (i am not thinking so) or somehow the freon top off affected the sensor in away that is not obvious.

i clear the error code but the same thing happens every time i take a ride. the ac continues to work fine. the car continues to drive fine.


I have researched the P2237 code here on priuschat and elsewhere. I see mixed explanations of what can be done or was done - for example: changed the sensor did nothing in many cases.

any ideas on where I can start to try and debug this issue?

 

Thanks for the helpful comment. if true, it would explain what otherwise appears to be a coincidence involving two unrelated components.

i will look around the area where the freon input valve is see if anything could have been disturbed. Perhaps when i nudged some things out of the way to get to that valve i disturbed something.

it is the upstream sensor (if I understand correctly), so I will follow the wire path from the sensor itself back up into the engine bay where the sensor clips in.

P2237 OBD-II Trouble Code: O2 Sensor Positive Current Control Circuit/Open Bank 1 Sensor 1