Low coolant, check radiator and resevoir, if its nit low there is a low coolant sensor that may be bad , this is a knon issue on these cars, sensor is located about 2-3 inches down under the radiator cap on passengersid
change your thermostat.
Build up in the radiator system or a plug can cause this. Do a radiator flush (or have a professional do it if you're not interested but it's fairly easy if you read an online HOWTO) to remove the grime and refill with fresh coolant. This solved the problem in my 2003. Check the low coolant level sensor and replace if defective. It is in the side of the radiator.
The radiator capacity for a 1998 Toyota Camry is two gallons. This includes coolant stored in the engine block and radiator.
On a 1998 Ford Taurus : The thread on cap on the engine coolant reservoir is the pressure cap / radiator cap
did u bleed the coolant system of air cuz that could be the reason
On a 1998 Ford Taurus : The thread on cap on the engine coolant reservoir is the pressure cap / radiator cap
On a 1998 Lincoln Navigator : The thread on cap on the engine coolant reservoir is the pressure cap / radiator cap
On a 1998 Ford Expedition : The thread on cap on your engine coolant reservoir is the pressure cap / radiator cap
the sensor is faulty. Located half way down the side of the radiator.
Blown head gasket.
On a 1998 Ford Taurus : The thread on cap on the engine coolant reservoir is the pressure cap / radiator cap
On a 1998 Ford E-150 : The thread on cap on your engine coolant reservoir is the pressure cap / radiator cap