If you see this error during heating nozzle/bed or during printing then printer has gone in protection mode to prevent risk of fire. This happens if temperature suddenly raises or drops a lot for around one minute. This can be caused either by printer being in too hot environment or then in really cold or drafty environment causing heat to raise/drop. Error could also be caused by thermistor issues like broken thermistor or bad contact in wire so please inspect thermistor cable on nozzle and replace thermistor if required.
There is also change that you have to just do PID tuning to get temperatures to keep in control so follow article about PID tuning