Couple of engine error codes and other issues?

[McDeth]

Well, I bought a 1997 4Runner with 149,987 miles on it a month ago. According to the used car salesman it was well taken care of, and it really did look as such. However, about 2 weeks after I got it the check engine light came on...greaaat.

I grabbed my dads ODBII code reader and it spit out the following codes;

P0131 Sensor Circuit Malfunction (Bank 1 Sensor 1

P0133 Sensor Circuit Slow Response (Bank 1 Sensor 1)

I'm going to go look the codes up right now, but does anybody have an idea what might be the culprit?

On another note, I have been driving the car around for about 3 weeks now with the check engine light on after I found what codes were causing the light to go off, and have not noticed any hits on performance or anything like that. However, today I started having some issues with the engine dying at idle speeds. The engine will start up and rev just fine, but whenever I let off the gas, the engine will die after slowly decreasing in RPM. Could this have any bearing on the two before mentioned error codes?

And while I'm here posting, I think I'll mention 2 other issues that I have been toiling with. First of all, the A/C button sometimes does not disengage. The button itself works fine, but the A/C light will sometimes not go off after the button is pressed. Pressing said button off and on several times helps the issue.

Secondly, the lights on the console on the A/C portion will always be off. If I hit the console they will come on. I'm hoping this is a connection issue more then anything else.

 

[toto]

Those codes are complaints about the oxygen sensor that's in front of the catalytic converter. Given that they're specific malfunctions of that sensor (those sensors do have some built-in diagnostic circuits), I'd start there.

The Mass Air Flow (MAF) sensor is known for causing strange behavior as well. There are other trouble codes for the O2 sensors such as "system too rich" or "too lean", but those are sometimes issues with the MAF rather than the O2 sensors. The MAF is located in the air intake duct right behind the air filter, and that's something that can usually be cleaned very carefully with electrical contact cleaner rather than replaced.

The A/C button and light issues I don't know about, but I agree that it sounds like an issue with electrical contacts somewhere rather than a system failure.