MAXTEMP error at startup
December 01, 2016 12:29AM
I am new to the forum but have been reading it for months and find it very helpful.
I have build a large printer running with a Rumba controller and DRV drives and Marlin firmware my problem is when i power up the printer it immediately tells me there is a MAXTEMP error and the print was halted and it needed to be reset.
I am in need of some assistance.
Re: MAXTEMP error at startup
December 01, 2016 06:05AM
I saw this happen on my printer before when I was first configuring the firmware. I had the wrong temp sensor. Once I picked the correct sensor type, the temp registered good after that.
Re: MAXTEMP error at startup
December 01, 2016 07:30AM
Chances are it is either an incorrectly defined sensor type, or a connection/wiring problem.

Re: MAXTEMP error at startup
December 01, 2016 11:01AM
The MAXTEMP error is a fail safe programmed in Marlin to shut down the printer should the thermistor become detached from the board or if the thermistor wire breaks (which does happen over time). When the themistor is detached the board registers a value of 0oC. The printer will continue to heat until 0oC equals your set temperature which will never happen, thus it will heat until your ceramic heater burns out, your printer burns up or your house burns down.

Other issues could be that:

1) Your connector for your thermistor is not seated correctly to the pins on your board. Take off the connector and reconnect it.
2) Your thermistors are attached to the wrong pins. I have seen a situation where a fellow poster attached a thermistor for Extruder_0 (Temperature_Sensor_0) to the pins for Extruder_1 (Temperature_Sensor_1) and another where the poster attached the thermistor for the heatbed to the same pins. In either case you get a MINTEMP error.
3) Your thermistor is bad
4) your board is bad.

These are the typical thermistors that are used with hotends and heat beds:


Do yours look like these? If so in Marlin your setting should be set to 1. That is:

#define TEMP_SENSOR_0 1
#define TEMP_SENSOR_1 0
#define TEMP_SENSOR_2 0

assuming you are using only one extruder.

Edited 2 time(s). Last edit at 12/01/2016 11:20AM by Lymphomaniac1.
Re: MAXTEMP error at startup
December 02, 2016 12:18AM
Thank you Lymphomanic1
My Marlin setting looks like the once you post. I will check the wiring and the type of sensor is the right one according to the supplier but will make sure myself.
Re: MAXTEMP error at startup
December 05, 2016 01:02AM
The type of Thermistor I showed is the one you need for the settings I provided. If yours look different, replace them with ones similar to the ones shown.

Another thing that can cause a MAXTEMP error is a dead short either at the tip of your thermistor (defective thermistor) at the terminal connectors or in your board (defective board). Change out your thermistors first, they are the cheapest thing to change out. Use ones that are pre-wired and have a connector at the end. See:

Re: MAXTEMP error at startup
December 09, 2016 01:52AM
Thanks for all the help.
I found the problem sensor was bad.
Re: MAXTEMP error at startup
December 13, 2016 04:45PM
I had a new thermistor go bad and now every one I connect gives me this error. I think it may have screwed my controller board... Anyone know if any other pins can be utilized for the hotend thermistor to see if it is just those two pins?
Re: MAXTEMP error at startup
December 13, 2016 06:28PM
Try the reset button on the control board, there is a lockout after a thermistor failure.
Re: MAXTEMP error at startup
November 19, 2017 11:44PM
Can a maxtemp error show if a board has a problem? i connected my thermister, and see a maxtemp error. When I short the thermistor, it shows 0 degrees celcius. Without the thermister, shows 500 degrees. with the thermsiter, or a 100k resistor, it shows about 470 degrees. I changed the power supply by thinking maybe the power was not enough (was testing with a 800ma PS). i fried the board by reversing the polarity by mistake. But was my board bad to begin with?
Re: MAXTEMP error at startup
November 20, 2017 04:28AM
You might just have the wrong type of thermistor selected in the config.
Re: MAXTEMP error at startup
November 20, 2017 09:34AM
If it is configured for a standard thermistor 100K resistor should show room temperature. Sounds like a wrong thermistor was set in the firmware, or you had an electrical problem.

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