Heater help

If this model has an electric coolant pump, they do get sticky and doesn't move coolant as efficiency as it should. Coolant control valve is also a high failure item at that mileage.They are mostly plastic and disfigure/wear-out over time. Have you been doing your recommended coolant changes? Check your HVAC coolant valve is opening up; allowing hot coolant into your heater coil.
You've got a sticky throttle body, needs cleaning out.

Hope this helps.

 

The P1121 indicates problems with the coolant flow control valve, which was replaced with a "new one off eBay" "months ago", so that seems to be about how long a "new off eBay" coolant valve lasts. The P1116 indicates incorrect behavior of the coolant temperature at the thermos outlet, which could quite easily be because of the faulty valve.

I suspect you meant to type B1442, right? That's a legit Gen 2 Prius heater code related to the air inlet servo. Heater codes are body (B) codes, not powertrain (P) codes.

There is some other model of car somewhere that has a "P1442" powertrain code about an engine air injection system. A Prius doesn't even have that system (or, naturally, that code), so googling for what it means in some other car is just a distraction when working on a Prius.

If you were able to see the old heater air inlet servo moving before you replaced it, probably that means the B1442 code was set by an electrical issue that was intermittent, and wasn't a problem right when you happened to look.

 

No, the 'thermos' is a large hot-coolant storage tank under the left fender. A problem with its outlet temperature much more likely indicates a problem with the coolant control valve. It is generally not coincidence when P1121 and P1116 both come up.

A Toyota coolant control valve from a dealer will probably last longer than months.

 

With some fancy equipment that very few people have, you can verify that the coolant valve is bad. Experience has shown that a P1121 is 95+% likely that it's the valve.

Toyota released a Technical Service Bulletin that states, you get that code, you should replace the valve.

You should first inspect the wiring for problems (like rodent damage). Then put a Toyota part in.

While you're in there, you might want to look around for any leaks or seeps. Usually if the coolant level goes down at all, then it's gotta be going somewhere.

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Though likely mistaken, you should be able to actuate the coolant control valve from within techstream.

 

Techstream or any capable scantool that has bidirectional controls should let you command the valve.

I have seen a few where the valve moved just fine, but the position sensor was glitchy enough to set a code anyway. Only "saw" the problem by putting a scope on the signal circuit.

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In Techstream, select Engine and ECT / Active Test - activate the water flow valve. The number 3, 4, or 5 denotes which of the three possible positions the valve can go to- 2.5V, 3.5V, or 4.5V (2.5V seems to be the default).

So select "activate the water flow valve 4" or 5, scroll the data list all the way to the right - water flow valve is 4th from the last data, hit the "right arrow" - it will go from off to on and the data should shift to the commanded position.

As mentioned, I often see the valve "work fine" on this test, but using a scope will show the bad position sensor that's triggering the code

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