Toyota Vios 1NZ engine coolant temperature

Question

Anyone have an idea about the normal coolant temperature of vios 1NZ engine.

When driving some times my overheat bulb blinks but the coolant level is normal and it is not boiling when I stop and open the engine bay. This happens often not regularly.

I have connected a Bluetooth OBD reader and the normal coolant temperature shown there is around 96C. Seems like the threshold for overheat bulb is 105C.

When I check the temperature in the cold start the OBD shows nearly correct environment temperature.

Can this be a temperature sensor failure? If the engine is overheated should the coolant be in boiling mode?

Appreciate your help. Thanks

Answer 1

It could be a coolant temp sensor issue - but I wouldn't rule out the possibility there's a real issue with the cooling system.

Coolant operates under pressure so a temp of 105°C doesn't necessarily translate to boiling coolant, in fact depending upon the coolant type and mix you're running I'd expect a boiling point of over 120°C

The readings you're getting for "normal" operating temperature sound about right and you say the "cold" readings are giving a near-enough values for ambient so that would say to me that the temp sensor is working. I'd suggest you may have a cooling issue - difficult to say what this could be on the information we have so far but if you aren't seeing any coolant loss then I'd be looking first at things that affect the efficiency of the system to remove heat, radiator fan, thermostat, coolant age etc.