Yaris / Echo sedan 1SZ-fe 1.0 L cooling fan trigger at high temperature

[Asadeng]

Dear all,

I have issue with my yaris installed with 1sz-fe engine. the issue is very strange . the cooling fan turned on at 206F or 97C while according to manual it should be at 200F or 93C. i have changed cooling temperature sensor. two wires. its mean the fan on and off controlling by ECU not from sensor. i have completed radiator service. have no issue with overheating problem but fan trigger on temperature should be less as per manual 93C. on AC switching on fan keep runs on

kindly help me to out for this issue.

[toyotavios_11]

could be fan relay issue, try to replace it

[komichal]

I would say this is normal.
The coolant boiling temperature is not 100 degrees Celsius but a lot higher and engines do need high temperatures to work efficiently. You do have a proper coolant in the system and not just plain water, right?
I would not suspect the relay either - the relay engages/disengages based on the info from the ECU. As long as it does engage - it is fine.

[Asadeng]

Dear Sir,
Thank you very much for your prompt answer, yes new coolant has been added. you really decreased my concern about knowing that the boiling point with coolant is not the same as normal water. i have installed odb2 application Torque on my din panel keep monitoring all activity of engine. while driving engine temp range varies between 80 to 90 in my hot zone. my AFR value is at optimum toggling around 14.7 its mean including temperature values from sensor to ECU is correct. Anyhow, thank you very much, sir.

[sh0rtlife]

in theory
if your thermostat is acting up it can "trap" heat in the engine and will be hotter than the temp switch is seeing as the switch is on the cold side of the cycle

its cheep and easy...