Traumflug: Only if it's shorted at the time you're looking at it (first time), and even then not as likely because the thermistor tables don't usually go that high.
Once you fry the input on a Mega (which tends to be anything over 5.5V), it tends to internally get locked at a fixed value. I've seen fixed readings through firmware of between 50-150C if the thermistor lead that goes into the Mega analogue input somehow gets connected to the 12V on the hot end (even if through some resistance - as the problem is caused by over-voltage on the analogue input pin of the Mega).
Once you fry the input on a Mega (which tends to be anything over 5.5V), it tends to internally get locked at a fixed value. I've seen fixed readings through firmware of between 50-150C if the thermistor lead that goes into the Mega analogue input somehow gets connected to the 12V on the hot end (even if through some resistance - as the problem is caused by over-voltage on the analogue input pin of the Mega).