For the last couple of months, I've had an intermittent code P2135 OBD-II Trouble Code: Throttle/Pedal Position Sensor/Switch A / B Voltage Correlation. It would come on once every 1/2 weeks, then disappear for a while when I cleared it. The car didn't seem any different in terms of performance, it was simply the CEL that illuminated.
In the last week or two, it's started coming on more and more frequently, and has been joined by the codes P0139 (O2 sensor circuit slow response) and P0116 (engine coolant temperature circuit range / performance). The car still seems to run fine, although I did notice that the fan seemed to be coming on more often than before. The temperature gauge is fine and it isn't losing any coolant.
I tried cleaning the throttle body as it was very dirty, plus the throttle body electrical connector, but that doesn't seem to have made any difference. When cleaning it, I noticed a slight electric crackling noise coming from the throttle body electrics: it was barely audible, and I'm not sure if that's normal or not.
I can get a new throttle body and I'm confident enough to fit it myself, but as they're not particularly cheap, and returning stuff where I live is a nightmare, I'd rather be sure that's the issue before I go ahead and order one. To me, it totally makes sense that it would throw P2135 and P0139, but the P0116 is bugging me a little as I can't see how that would be related to the throttle body.
Any ideas? Should I just go ahead and change it or is there something else it could be?