Toyota Repair: Tacoma engine light, obd2 code reader, drivability problems

Question
Hi,

I have a 96 Toyota Tacoma 4WD, extra cab, 3RZFE engine (2.7 Liter, 4 cyl). It has 114K miles.  I have a check engine light. There isn’t any change in drivability, or any noticeable change in gas mileage. I just replaced the cap, rotor, plugs, fuel filter, air filter.

The OBD2 code reader gives me a code 0141, which my chart says is: 02 sensor heater circuit malfunction (bank1, sensor2). I assume this means that 02 sensor #2 is shot. Is it possible that the heater relay is bad? Can I check either with a VOM?

My question is, is 02 sensor #2 the one after the cat? This seems to make sense, because I assume a bad sensor before the cat would result in noticeable drivability problems. Also, assuming that I replace the bad sensor, will the check engine light go out automatically, or does it need to be reset? If so, how do I reset it?

Thank you.
PS: I had submitted this question before, but I think it got lost. Sorry if it's a duplicate.

Answer
The solution for this is to replace the O2 sensor located behind the catalytic converter, the reference to the heater circuit means that the sensor's heater circuit has a malfunction, this built into the sensor to heat it up with an electric current before the exhaust heat does so, this is for emission control reasons on cold starts.
After replacing the sensor try disconnecting the negative battery terminal to clear the trouble code.