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If the car's computer does not receive a temperature signal due to a short circuit or some other fault, then the car will automatically be placed in limp mode as a precautionary measure. The temperature measurement problem will need to be rectified before the car will come out of limp mode.
Have you recently been driving in an area of heavy rain or flooding? Water getting into the engine compartment is the most common cause of a short circuit.
The temperature sensor is part of the thermostat housing, located on the right hand side of the engine block, above and to the right of the TDC sensor. Check there for any loose wires first. Use a multimeter to check if a signal is being sent from the sensor.
If the sensor is faulty (a common fault on these Meganes) it will need to be replaced.
Thanks for the update, Richard.Please take a moment to rate my service :)You can still reply back at any time.Pete.
The sensor is likely supplied as part of the complete thermostat housing and not individually, so you will need to replace the complete housing.