245C is reasonable for ABS. It it hard to recommend an exact value because it depends on the type of ABS, where the thermistor is mounted and if you have calibrated it (most thermistors are only +/-5% accurate).
If it is not hot enough it will be difficult to extrude because it will be too viscous. Also the layer bonds will be weak.
If it is too hot it will start to discolour and may smoke.
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