Sensor next to throttle housing on intake manifold???

That is the manifold absolute pressure sensor.

As the name implies, its reading is always nonnegative, around 101kPa (atmospheric pressure) when the engine is stopped, dropping to a smaller number (a relative vacuum) when the engine is running.

One thing at least that it is used for is confirming that the EGR system flows as designed when the ECM tests it.

 

I used MAF (Mass Air Flow) sensor cleaner (very clean, like electronics cleaner I think), but it does look pretty durable.

An oil catch can will help some, to keep it clean. Otherwise it's practically swimming, in the dreck introduced by the PCV (Positive Crankcase Ventilation) circuit.

 

2013 Prius. MAP Manifold absolute pressure sensor. Be careful when replacing the air filter housing. If the breather hose gets under it during installation it can unplug the map sensor plug. Had this happen to me. Notice in the picture the MAP is unplugged. That was after I noticed the air filter housing wasn't going on very well. The breather hose was under it instead of beside it (toward the front.)

 

@Georgina Rudkus has been posting avidly about the firmware update available to ward off misbehavior of the purge valve.

 

Rankles that the dealerships have to “wet their beaks”, charging for a few minutes of software update.

 

They have to follow a fairly elaborate procedure to disconnect or disable large unpredictable electrical loads, and dig down to your aux battery and hook up a GR8, all to try to minimize any chance of a power flicker during the update leaving your car a brick. Then they have to unhook the GR8 and put everything back the way it was. If they can get through all that in "a few minutes" they're faster than I am.

You can make it easier on them by cleaning out the back before going in for the update, since they have to get down to the battery anyway. And if you have any electrical loads you've added that they don't know about, be sure to disconnect those if there's any chance they could cycle on during the procedure. (I've added an air compressor that I'd better remember to disconnect before going in for any update.)

 

Oops, no one called me on this. That is an anti freeze cooling hose. This one is the crank case ventilation hose that slides off if the purge valve is bad. Sorry.