Max Temp Error At 295C Please Help!

I am running Marlin 2.1. I have adjusted the maxtemp setting for every heater to 475. I am running an E3D Hemera extruder with a PT1000 temperature probe. The correct pull up resistor has been installed. I have searched Marlin settings for hours, I have adjusted everything I can think of. For some reason I always get an E1 maxtemp error at 295C on the extruder. It seems like it should be an easy fix but I have never been so frustrated. Can anyone help me with this? Do I need to attach configuration files or anything? Any advice or suggestions would be greatly appreciated.

No mention of what thermistor type you selected in marlin, or what pull up resistor it has... so can only guess at the table used

Im going to guess type 1010 as

// Pt1000 with 1k0 pullup
constexpr temp_entry_t temptable_1010[] PROGMEM = {
  PtLine(  0, 1000, 1000),
  PtLine( 25, 1000, 1000),
  PtLine( 50, 1000, 1000),
  PtLine( 75, 1000, 1000),
  PtLine(100, 1000, 1000),
  PtLine(125, 1000, 1000),
  PtLine(150, 1000, 1000),
  PtLine(175, 1000, 1000),
  PtLine(200, 1000, 1000),
  PtLine(225, 1000, 1000),
  PtLine(250, 1000, 1000),
  PtLine(275, 1000, 1000),
  PtLine(300, 1000, 1000)
};

This table only goes up to 300

Yes it is set to 1010 with the 1k pullup. I have been using the config for several months now and it works fine I just wanted to try printing some PC and now am running into issues. I don't understand the table you posted. Would you please be so kind as to briefly explain what it is for, where you found it, and how to modify it if that is indeed what is limiting the temperature? Thank you for your time.

I found the table. Now just to understand what it does and how to modify it. I would assume just adding a few more lines to the end but I am not sure.

Every thermistor type number is basically used as a table name and file name

type 1010, marlin loads file Marlin/src/module/thermistor/thermistor_1010.h

In there it has table temptable_1010
This is a table of how to convert ADC values into temperature.

You cannot exceed the lowest value or the highest value listed in this table.

You could try updating the table to the following.

constexpr temp_entry_t temptable_1010[] PROGMEM = {
  PtLine(  0, 1000, 1000),
  PtLine( 25, 1000, 1000),
  PtLine( 50, 1000, 1000),
  PtLine( 75, 1000, 1000),
  PtLine(100, 1000, 1000),
  PtLine(125, 1000, 1000),
  PtLine(150, 1000, 1000),
  PtLine(175, 1000, 1000),
  PtLine(200, 1000, 1000),
  PtLine(225, 1000, 1000),
  PtLine(250, 1000, 1000),
  PtLine(275, 1000, 1000),
  PtLine(300, 1000, 1000),
  PtLine(325, 1000, 1000),
  PtLine(350, 1000, 1000),
  PtLine(375, 1000, 1000),
  PtLine(400, 1000, 1000),
  PtLine(425, 1000, 1000),
  PtLine(450, 1000, 1000),
  PtLine(475, 1000, 1000),
  PtLine(500, 1000, 1000)
};

Then carefully test it.

You sir are a genius! I am now able to go over 295C. Very exciting. I never run my printer when I am not home as I feel my DIY heated chamber does not have as many failsafes as I would like. Also I keep a giant CO2 fire extinguisher next to it. So I will certainly carefully test it. Thank you so much!