Diagnosing: Thermostat vs. Coolant Temp Sensor

[jactre]

Originally Posted by M302_imola

That's exactly what I did. Crazy thing is I did an oil change right before the kit showed up and the CEL vanished. Radiator fan quit working overtime and oil temp start to rise to normal. Drove the car 100 or so miles and then just like I suspected it triggered another CEL. I'll get the t-stat and waterpump replaced next week.

I don't understand why the engine coolant temp would be low(never getting up to temp), and the fan would be on full blast.

I'm having a similar issue but I changed the pump and thermostat 2 months ago.....

[tlow98]

Originally Posted by jactre

I don't understand why the engine coolant temp would be low(never getting up to temp), and the fan would be on full blast.

I'm having a similar issue but I changed the pump and thermostat 2 months ago.....

It’s a fail safe mode. If the car is not certain what data it’s getting… in this case conflicting information from multiple sources… it will try to save itself in what it suspects is the worst case scenario.