high temp. for seconds then disappear

DTC P1150 might mean a coolant system clog but it also could be caused by:

1. CHS tank outlet temperature sensor
2. Coolant flow control valve
3. ECM (aka engine ECU)

Since the symptoms started immediately after your dad's little accident, I would start by checking the temperature sensor mounted at the output of the coolant tank. First, measure the resistance of the sensor while it is installed. The resistance should be somewhere around 2K-3K ohms at temperatures around 25 - 30 degrees C.

Then remove the sensor and see how it responds to very cold and very hot water. Put it in a cup with ice water, and measure the sensor resistance, which should increase to around 6K ohms or so. In boiling water the resistance should decline to around 200 ohms. Keep water off the sensor terminals.

If the sensor is producing erroneous readings, this may cause the ECM to think that the coolant flow is impaired.

Regarding the momentary high temp indication, have you checked engine coolant level at the reservoir mounted behind the radiator, as well as at the radiator cap when the engine is cold? You need to remove the black plastic cover over the radiator to access the cap, and use Toyota Super Long Life Coolant to refill as needed (pink color coolant.)

Good luck.

 

" Hot water temperature in the coolant tank" Are you referring to the thermos bottle? If so, under hard driving, that water will eventually get hot, as the hot water from the engine cooling system also circulates thru the thermos bottle. At that point the radiator should be warm to hot and the radiator cap should also be warm to hot and release with pressure. The Prius is not a hot running car, I recently changed the inverter pump and put new coolant in and had extreme difficulty getting the thermostat to open. Perhaps the temperatures in Jordan are much hotter than California. Electronically I can't suggest anything, I will leave that up to Pat. When the engine,and radiator are hot, can you see any turbulence at the open radiator cap? On a normal car, that is the case, on a Prius, I don't know. What is the temperature at the radiator cap, when hot? Measure it with a thermometer. If that temp is hot then your thermostat is opening and you have some blockage somewhere. (Be careful removing cap and use a rag) I assume the inverter cooling system is normal?.It may sound crazy but are you turning the cars heating system to maximum to allow total recirculation? This is also a method for cooling a overheated engine/ water circulation system. That's all I can think of: One more point, after opening up the engine coolant system, did you bleed all the air out ? Look at Coolant heat storage on PriusChat.

 

did anyone mess with the radiator fan?

Perhaps the blades are reversed?

 

Hello Othman, How are you and your Prius doing?

 

I've never seen the high temp icon, my web search found:

Red thermometer over horizontal wavy lines on MFD - high coolant temperature warning light. If this goes off, do see your dealer, as you shouldn't see this unless something is mechanically wrong. (Prius driven through Death Valley at high speeds in the summer don't even get this...)

Red car with an exclamation point on it on MFD - hybrid system warning light. If this goes off, do see your dealer, as you shouldn't see this unless something is mechanically wrong.

so, you did see the first one, right? I could see the second icon being misinterpreted for the first.

 

i went so a normal mechanical . he told me to push hard at the fuel pedal while the gear is at (P)
he only added some water & then managed to reset the computer in the same way when i would change the oil (keep pushing over <trip> click & clicking the <power> button two times without the leg on the break pedal & then with pushing on the break pedal)
the amazing thing which i still CAN'T understand & i hope someone would help me in the understanding is that the car didn't show any error or check engine light since then.
when that guy re-setted my car's computer, the heater went back to normal
i wish to understand what was the exact problem.. & did it resolve or just hidden someway by this maneuver?

If your car functions normally with no error codes, the engine problem should be fixed. Accelerating the engine is useful in getting the air pockets out of the engine coolant loop ( it increases the pressure in the coolant system) , resetting the light is only an electronic 'coincidence' in this case.

Accelerating the engine will not affect the inverter coolant pump. You say
the fluid is not mixing-up very actively as i remember when we bought the car; but still somewhat better than b4 changing the pump..
Here is a video of a prius inverter reservoir , it is low pressure, but you can definitely see flow. How does it compare to yours?
YouTube - Gen 2 Prius Inverter Water Pump Flow

 

Your posts are hard to read and understand.

Just trying to help you.

Please see jdenenburg's new post in Gen II Main Forum concerning new
recall on Inverter pump failures causing high temp spike.

 

Ok... I have seen this issue before, and it is easy to fix. I did mine myself.
Here is what I have gotten from your posts that have lead me to the fix...
The front end was struck and you moved the pump and coolant tank. You opened it to inspect it.
You had an intermittant heat warning light...
The part that gave me the biggest clue to your issue with the heater not working.

I had the same problem when the dealer replaced the coolant bottle on mine and did not completely bleed all the air out of the system. It was Friday night on a holiday weekend and I had to work (50 mines away) the next night... Even a SMALL bit of air will cause a problem with the Prius.

How to fix it:
Get a gallon of the special LL coolant for the Prius from the dealer or NAPA (make sure its the RIGHT stuff (pink)).
Park the Prius on as level a place front to rear as possible or with the front slightly raised (like in the driveway) (curb is OK in front of the house).
With the engine COLD:
***** BLOCK THE WHEELS AND SET THE EMERGENCY BRAKE *****
Remove the plastic cover over the radiator.
Remove the radiator cap.
Squeeze the top and bottom radiator hoses a few times to expel air in them.
Pour coolant into the radiator until it is halfway to the top.
Squeeze the top and bottom radiator hoses a few more times to expel air in them. When the level drops in the radiator, add more coolant.
On the right side of the radiator (fender), there is a hole. Look into the hole. There is a hex nut there (to purge the air). Turn the nut to the left. Pour coolant into the radiator until it just starts to come out the hole, then turn the wrench right to close it.
At sevaral points in this, you can squish the hoses to let out more air.
Leave the radiator cap off.
Now the fun part. Be careful from here on! The coolant will get HOT!!!!!!!!!
With the EMERGENCY BRAKE ON, press in the normal brake and hit the power button (ready mode). Open the windows. Turn the heater temperature all the way to its highest setting. The engine will start and will cycle on and off every few minutes.
While the engine is warming up, keep topping off the coolant.
At some point, the thermostat will open. You will notice a sudden drop in the coolant level, so be ready to add coolant!
It should take about 30-45 minutes to get the air out of there.
I knew it was fine when I was getting a lot of heat out of the heater.
When you are done, button things up and top off the resevior (sp).
In a day or 2, remove the panel again and check the level. U might have to do the bleed procedure again (I did not), especially if you hear air bubbles in the heater. Keep an eye on the levels in the reservior... If it gets lower, you still have air in there that is getting expelled.
And... Here is an official :welcome: to the forum!!!!!

And... You could always pay the dealer $150-$200.00 to do this with their magic vacuum thingy...

 

welcome to the club man, i thought im the only one in Jordan and says the only toyota dealership is bad, im also doing and fixing stuff my self with help from the great guys here

 

MANY Thank's to magic-man... your procedure was just the trick to get the air out of my coolant loop after having to swap out the coolant hoses to the air intake. Doing so allowed me to clear two error codes P1121 & P1150 that were caused by air in my coolant loop.