Haynes says........

On all models the coolant temp gauge/warning light sensor is located in the
coolant outlet union on the left hand side rear of the cylinder
head..............this obviously only applies to 4 cylinder engines. If you
have a V look in the same area though. It does say the sensor can be renewed
which I think would be obvious.

That is about a 10 minute job to replace the Coolant Temperature Sensor if
the one for the FI is the same one.
Right at the rear of the cylinder head.
Make sure the engine is cold, loosen the coolant expansion tank cap and then
retighten.  This releases any pressure in the system and stops/slows any
coolant loss.
Then you can either pull the clip holding the sensor and pull the sensor out
with the wiring plug attached.  Then install your new sensor along with a
new 0-ring after making sure the old 0-ring is out of the hole.
Install clip and clip on wiring plug.
You probably will not lose any coolant.  ;-)
BTW I don't think that sensor is expensive at the dealer, but call and
check!