P0712 code on Vitz and CVT fluid overflow from breather hole

[riztauras]

Hello All,
So I was driving my Vitz 2005 F1.0 yesterday on Karachi Hyderabad Motorway just after crossing bahria town, check engine light appeared. My ELM327 adapter was already connected to the car so while driving I checked the code on Toyota ELM app.
The code was "P0712 Transmission Fluid Temperature sensor A low input"
so I parked the car on next gas station about 2 km ahead after code appeared.
I opened the hood and saw that CVT fluid was coming out of air breather hole (the hole reference is shown in attached picture).
so there was a local mechanic near by gas station I asked him if it is safe to continue my journey for about 180 km more.
He said yes but do not go above 80-90KM/h.
So I let the car cool a little for about 10 minutes and then continued my journey, the check engine light cleared on its own without any other intervention and I faced no problem in driving for 180Km more and reached home safely.
On reaching home I again checked the breather hole there was "no more" fluid coming out.
Can anyone tell me what happened here?
I am not an expert but guessing the CVT fluid was a little overfilled by previous owner.
I purchased the car 2 month ago and driven a total of 500 Km mostly short distances within city.
Can anyone tell me what is the way ahead, I guess I need to change the CVT fluid as the previous owner who kept the car for about 2 years didn't change the CVT fluid either so it must be due for change.
Please any expert on the subject can give me the advice or way forward please...!

[capsat]

Is transmission cooling lines connected to radiator bottom

When was the transmission fluid changed?

Never so far? Time to change and adopt correct procedure already mention in a thread over this forum

It seems the overfilled fluid seeped out under Constant high speed Function

@ser_gtr @syncview @xulfiqar

[Xulfiqar]

This transmission is stupid - it has a cooling donut on the transmission where coolant goes, unlike our regular ones where transmission fluid goes to radiator to cool down.

That little cooling donut can clog with rust/debris/corrosion if proper coolant is not used - and then you get overheating transmission as a bonus.

[riztauras]

@Xulfiqar bhai can you advice what should be done next?
I am sure I need to change transmission fluid, what else I should do to unclog the coolant donut as you said?

[riztauras]

No idea when transmission fluid was changed because last owner didn't change it. and I don't know about second last owner.
Cooling lines to radiator? No idea what that means can you elaborate please.

[iqbalu140]

The transmission fluid needs to be cooled down. It is pumped by the transmission into the radiator, water and transmission fluid cooling lines are separate.

[riztauras]

Ok I checked in Vitz transmission fluid doesn't go to radiator for cooling instead radiator water based coolant is sent through hose pipes to cool transmission.
I guess something is wrong with those hose pipes or a clog somewhere in water jackets or in transmission.

[Xulfiqar]

Thats the donut i mentioned

[riztauras]

Yes you are right. Any advice for me please?

[umarirshad266]

Assalam o alaikum bhai same issue with my vitz 2007 check engine light on 120 speed and as i slow down speed to even 110 it vanishes. I scanned my car p0712 error code appeared temperature sensor low input. But when mechanic tightened the temperature sensor grips it vanished. I still not checked it on 120 speed but suggest me only after tightening sensor grips my issue resolved or not what I have to do further?