# Heater not heating at expected rate **URL:** \ **Category:** General Discussion\ **Created:** [January 31, 2025, 6:20pm UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738 "2025-01-31T18:20:02Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![vierringe](https://avatars.discourse-cdn.com/v4/letter/v/b5e925/32.png) [@vierringe](https://klipper.discourse.group/u/vierringe)\ **Post date:** [January 31, 2025, 6:20pm UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/1 "2025-01-31T18:20:02Z")
### Basic Information: Printer Model: Anycubic I3 Mega s MCU / Printerboard: stock Host / SBC klippy.log [logs-20250131-185609.zip](https://klipper.discourse.group/uploads/short-url/lDeY6SPwLTPEdc43ivcSZNqzdpS.zip) (141.3 KB) [config-20250131-185603.zip](https://klipper.discourse.group/uploads/short-url/5NewRwvEMHm1C7qIaMRbwKUq9sU.zip) (1.3 KB) Hello everyone Yes, I know this must be the thousandth thread about this topic, but unfortunately I just can’t get any further. I have already tried all the solutions of other threads without any success. I get the error “heater extruder not heating at expected rate” more or less at random. I have already tried all the changes in the config file. Most recently I even set the min\_extrude\_temp to 0. The error still came back. I have also already replaced the complete hotend. This includes the sensor and the thermistor to rule out a hardware error. What else can I do? I really don’t know. The error starts in line 3940 of the log file. You can see the temperature jump of almost 100 degrees. How can that be? I hope someone can offer me a simple solution here. It is enough for me to simply adjust the config file so that the printer runs. I never let it run on its own anyway. ---
**Author:** ![NAPCAL](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/napcal/32/1794_2.png) [@NAPCAL](https://klipper.discourse.group/u/NAPCAL)\ **Post date:** [January 31, 2025, 6:46pm UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/2 "2025-01-31T18:46:01Z")
Thermistor: More than likely a failing connection, maybe a frayed wire contacting the frame or metal housing. A not fully broken wire, causing an intermittent break or grounding. Movement of the connector wire causing an intermittent break or additional resistance. Check these while on to see if you can cause the spike. Also, you might look into these adjustments > [verify\_heater extruder] > #max\_error: 120 > #The maximum “cumulative temperature error” before raising an error. Smaller values result in stricter checking and larger values allow for more time before an error is reported. > #Specifically, the temperature is inspected once a second and if it is close to the target temperature then an internal “error counter” is reset; otherwise, if the temperature is below the target range then the counter is increased by the amount the reported temperature differs from that range. Should the counter exceed this “max\_error” then an error is raised. The default is 120. > check\_gain\_time: 50 > #This controls heater verification during initial heating. Smaller values result in stricter checking and larger values allow for more time before an error is reported. > Specifically, during initial heating, as long as the heater increases in temperature within this time frame (specified in seconds) then the internal “error counter” is reset. The default is 20 seconds for extruders and 60 seconds for heater\_bed. > #hysteresis: 5 > #The maximum temperature difference (in Celsius) to a target temperature that is considered in range of the target. This controls the max\_error range check. It is rare to customize this value. The default is 5. > #heating\_gain: 2 > #The minimum temperature (in Celsius) that the heater must increase by during the check\_gain\_time check. It is rare to customize this value. The default is 2. ---
**Author:** ![3dcoded](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/3dcoded/32/20297_2.png) [@3dcoded](https://klipper.discourse.group/u/3dcoded)\ **Post date:** [January 31, 2025, 7:23pm UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/3 "2025-01-31T19:23:14Z")
At 20:54 in your log, the extruder thermistor suddenly drops in temperature. ![Screenshot 2025-01-31 at 2.20.43 PM](https://global.discourse-cdn.com/free1/uploads/klipper/original/3X/2/6/26c2f91f89ee955a6ff8ec15190be01ee920b6f9.png) As @NAPCAL said, this could be a failing wire. Your thermistor could also have fallen out of your hotend. Either way, Klipper just prevented thermal runaway (a fire). ---
**Author:** ![vierringe](https://avatars.discourse-cdn.com/v4/letter/v/b5e925/32.png) [@vierringe](https://klipper.discourse.group/u/vierringe)\ **Post date:** [January 31, 2025, 7:55pm UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/4 "2025-01-31T19:55:32Z")
Thanks for the quick answers. To be more specific. I already had the problem with my old hotend. I suspected a hardware problem and ordered a new one. I also looked at this thoroughly before installing it. All cables looked ok and were not damaged or kinked. Even now after several troubleshooting sessions everything still looks fine. So the question is, where is Klipper reading this wrong value so suddenly? I will try the parameters described by @NAPCAL. Maybe they will at least stop the shutdown. ---
**Author:** ![Sineos](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/sineos/32/18_2.png) [@Sineos](https://klipper.discourse.group/u/Sineos)\ **Post date:** [February 1, 2025, 8:45am UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/5 "2025-02-01T08:45:53Z")
From the laws of physics, such sharp temperature drops are impossible. When one experiences such drops, they are usually due to some hardware defects, typically around the thermistor. I would not recommend playing with the heater’s settings. While you might be able to “hide” your issue and force Klipper to continue, it will not solve the problem and may create additional unwanted effects. ---
**Author:** ![Slow](https://avatars.discourse-cdn.com/v4/letter/s/b9bd4f/32.png) [@Slow](https://klipper.discourse.group/u/Slow)\ **Post date:** [February 5, 2025, 5:07am UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/6 "2025-02-05T05:07:07Z")
Sineos is right: such sharp temperature drops are impossible. The 3D printer is a complicated machine with a lot of wires and parts. Maybe something has gone wrong with one of these components. It may not actually be the hotend thermistor but something else in the machine… (sorry if I did or said something wrong here, I’m kinda new to this…) ---
**Author:** ![Slow](https://avatars.discourse-cdn.com/v4/letter/s/b9bd4f/32.png) [@Slow](https://klipper.discourse.group/u/Slow)\ **Post date:** [February 5, 2025, 5:07am UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/7 "2025-02-05T05:07:55Z")
Like the wire connecting the hotend to the rest of the machine. ---
**Author:** ![NAPCAL](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/napcal/32/1794_2.png) [@NAPCAL](https://klipper.discourse.group/u/NAPCAL)\ **Post date:** [February 5, 2025, 5:36am UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/8 "2025-02-05T05:36:41Z")
@Sineos, I think my debugging advice got misunderstood. I was recommending making changes in the [verify\_heater extruder] section temporarily to hold off the shutdown so the wiring fault could be found by watching the temperature graph and tracing it down. Then, after the repair has been confirmed, I would return the [verify\_heater extruder] section to its default. ---
**Author:** ![Sineos](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/sineos/32/18_2.png) [@Sineos](https://klipper.discourse.group/u/Sineos)\ **Post date:** [February 5, 2025, 5:51am UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/9 "2025-02-05T05:51:59Z")
Indeed, I might have misunderstood the intention. This makes sense, of course. Thanks for clarifying, @NAPCAL. (Actually, I was already surprised to read such a comment from you 👀 ) ---
**Author:** ![vierringe](https://avatars.discourse-cdn.com/v4/letter/v/b5e925/32.png) [@vierringe](https://klipper.discourse.group/u/vierringe)\ **Post date:** [February 5, 2025, 6:12am UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/10 "2025-02-05T06:12:36Z")
@NAPCAL your advice helped me a lot. Printer is running fine since i implemented these commands. Next step is to find the main reason for this error. But for now i’m fine with this solution. Maybe after 5 years time has come for a new and bigger one. ---
**Author:** ![Sineos](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/sineos/32/18_2.png) [@Sineos](https://klipper.discourse.group/u/Sineos)\ **Post date:** [February 5, 2025, 6:20am UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/11 "2025-02-05T06:20:31Z")
> [@vierringe](#): > > But for now i’m fine with this solution. Exactly, this should not be the case. This is not, and in no way, a solution—it is merely a debugging advice and not a fix. You are experiencing an issue, and now it is just hidden, likely causing problems that could lead to catastrophic failures. I removed the solution tag. ---
**Author:** ![NAPCAL](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/napcal/32/1794_2.png) [@NAPCAL](https://klipper.discourse.group/u/NAPCAL)\ **Post date:** [February 5, 2025, 6:39am UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/12 "2025-02-05T06:39:39Z")
@vierringe, I fully agree with Sineos. Since the temperature reading doesn’t seem to show a drop below zero per the thermal graph, even though the klipy log does, it would be very difficult to get direct feedback from the log. You will need to use the temperature graph during the print head movement to find a common movement that triggers the quick temperature drop. This can lead you to the area of the fault. The section [verify\_heater extruder] is a safety feature that shuts down the printer to prevent the room where this printer is located from burning. So don’t leave the printer unwatched when printing. Basically, it has detected an abnormal reading, so it doesn’t know if the hotend is heating beyond the safe operating boundary, so to be safe, it shuts down. ---
**Author:** ![Sineos](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/sineos/32/18_2.png) [@Sineos](https://klipper.discourse.group/u/Sineos)\ **Post date:** [February 5, 2025, 6:43am UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/13 "2025-02-05T06:43:02Z")
@NAPCAL, this is exactly the typical reaction when pointing users to such settings (at least from my experience): 1. Oh, the engine control indicator of my car is lit bright red. 2. Let’s put a nice smiley sticker on the light. 3. Voilà, I don’t see it anymore. Problem fixed. This is also the difference between, e.g., Marlin and Klipper, which quite a few users do not appreciate: Marlin: “See, I have put a nice red light up. You may safely ignore it; it only has decorative purposes, and I won’t bother you with any pesky actions.” Klipper: “Here you have an ugly error message, and I’m not going to move a millimeter unless you fix this crap.” ---
**Author:** ![NAPCAL](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/napcal/32/1794_2.png) [@NAPCAL](https://klipper.discourse.group/u/NAPCAL)\ **Post date:** [February 5, 2025, 6:46am UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/14 "2025-02-05T06:46:15Z")
> [@Sineos](#): > > - Oh, the engine control indicator of my car is lit bright red. > - Let’s Ok, Penny (Big Bang Theory) oh, the check engine light is on, I got to remember to put a sticker over that. ---
**Author:** ![EddyMI3D](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/eddymi3d/32/1981_2.png) [@EddyMI3D](https://klipper.discourse.group/u/EddyMI3D)\ **Post date:** [August 2, 2025, 12:26pm UTC](https://klipper.discourse.group/t/heater-not-heating-at-expected-rate/21738/15 "2025-08-02T12:26:20Z")