Alternator light on and coolant temp hot - 1995 Jaguar XJ6

your needle may be giving you a false reading try a secondary measurement like an infrared meter a red light indicates max temp of your coolant has been reached and you suppose to pull over and allow to cool immediately when light is emitting if you dont see your coolant boiling over i would recommend replacing your temp sensor

Add to coolant Sensor is reading low coolant level in overflow bottle

the low coolant sensor is located inthe over flow bottle thay go bad

un do the hot side of battery for 5 to 10 min that will reseat the caputer

Check your belts.

year, make, model, and engine size?

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YOUR TEMP GAGE WILL NOT REGISTER CORRECTLY WHEN THE COOLANT FALLS BELOW A CERTAIN LEVEL. WHEN IT IS SMOKING IT IS EXTREMELY HOT. IF YOU HAVE A COOLANT LEAK THAT BAD IT SHOULD BE NOTICEABLE EVEN WHEN IT IS NOT HOT. YOU NEED TO FIND THE SOURCE OF THE COOLANT LEAK. WATER PUMP, COOLANT HOSE, FREEZE PLUG, HEAD GASKET, RADIATOR CAP LEAK, OR RADIATOR, OR HEATER CORE. CHECK THE ABOVE AND YOU WILL FIND THE SOURCE OF THE LEAK.

It is possible, how ever, I would check for inop coolant fan, or restricted radiator. If parts of the radiator are cool to the touch when the coolant fan has kicked in, very possibly resricted flow of coolant through the radiator.

the coolant could be just overflow,, as far as the temp,, replace the thermostat as a first thing, when your car gets that hot, it causes readings to be sent to the computer that sends mixed signals to other parts of the car, The first thing you should do is pull the diagnostic codes. This will tell you if the thermostat is dead.check the temp sending unit, it is located under the upper radiator hose, 19mm wrench will take it off, it costs about 20 bucks but you also need to replace the thermostat. all in all its about 25 bucks total and all your gauges work fine....

think it needs more coolant added when engine is cold

The coolant temp sensor probably cracked and reading wrong. On drivers side of head. The lower one, with 2 wires going to it.