Mk3 prius over heating coolant sighn

Hi
Car :
2014 prius mk3 , 150k mileage
6-7k oil changes been done ,
My car has started displaying the coolant sighn red ,last 3 month this started ,
ABOUT once a month it comes & stays about 15-20 seconds, then goes away , no triangle or power loss ,
I have a Bluetooth obd with adapter ,
I scanned with car scanner & another one can’t remember name ,
NO CODES

I cleaned the intake manifold 4-5 months ago that improved cars smoother , I will get the egr & cooler along with new coolant & I suspect water pump ,inverter coolant also on list ( is thermostat recom) in uk dealer water pump price £365 expensive !
Before I start replacing, how can I be sure

What’s the best cheap apps for diagnostic
Thanks

 

No coolant leak ,
Or coolant loss ,
Did the intake manifold 3 months prior , made it smoother

What’s best Bluetooth app to check for codes

the coolant hasn’t been changed ,
Is the thermostat changing recommended if I change water pump
Will try to clean egr as well all in one go

the bloody Toyota uk want £364 for water pump that’s with discount & 160 for thermostat ,

How can I check water pump ,
I don’t have tech stream ,
I have a Bluetooth obd2 adapter

thanks

 

Thanks guys for help I’m going to order a original water pump ,

would you guys recommend replacing thermostat also ,
It’s over heated about 3 times in 3 months

 

I heard so much about Aisin , I don’t want to risk it , plus too long to deliver , & too cheap to be genuine

what about thermostat what would you say please


Also how much coolant do I need , is it 5 litres uk or more

thanks

 

Thanks
Ordered one from eBay (I know risky)
100 % feedback & seller business registered only selling Toyota Lexus parts
£250 with postage next day
long time trader ,
plus I’m worried about my over heating, plus I drive taxi can’t wait , if I had time prob would of got the Aisin ,

should I replace thermostat do you think ,
Or should I try the pump first & see how it goes first ,
Locally not getting over heat & I did a 120 mile round trip no prob ether ,
Just every once a month it happens randomly again locally diving

Others say it’s very reliable, the Toyota thermostat

It would be aftermarket one like febi I can get quicker ,
Aisin would be about 2-3 weeks postage time


Let me know what you think please

 

Thanks specially Brian & mendel
I will definitely update ,
Is there anything extra I should do when bleeding air ,
I know to put car on maintenance mode & let fan come on twice ,
Is leaving coolant cap off better , that’s what I think , & squeezing hoses not sure which ones , the top hose on cooler ?

also this amayama site for original parts seems awesome if times no issue ,
Might order a thermostat £30 delivered ,
In uk dealer £160 crazy .

 

Hello guys update

the water pump was bad , compare to new it had about 60-70 % more resistance & impeller swollen & cracked ,
& I like opening things ,

only one question the bleeding went perfect ,
Took a long time for fan to come
But I may have over filled ,full 5 litres
I poured in & squeezed the hoses & poured til b line , & ran on maintenance mode about 45 - 60 mins for fan to turn on twice

Now after cooling & settled , it’s sitting just above Maxline , ( my car parked upwards 25% inclin on driveway
Is that a issue or should I drain little