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Temperature, Heating, and Extrusion Errors

This page organizes errors related to temperature sensors, heaters, heated beds, extrusion, and filament runout detection. For temperature protection errors, first verify the hardware and temperature curves. Do not bypass issues by disabling protection.

Error 'XXX mcu' shutdown: ADC out of range​

Error Message: ADC out of range, abnormal temperature detection.

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Cause: Klipper detected a temperature beyond the configured allowable range. Common causes include an open or shorted thermistor, wiring errors, incorrect thermistor model configuration, or pin configuration errors.

Note

Temporarily relaxing min_temp and max_temp is only for troubleshooting and should not be used as a long-term configuration. After confirming the issue, restore safe limits to avoid disabling temperature protection.

Troubleshooting Sequence:

Power off

Before checking thermistors, heater cartridges, heated beds, fuses, SSRs, MOSFETs, or power-related wiring, completely turn off the printer and disconnect the power supply. Allow the hot end and heated bed to cool. Do not disassemble the power supply, touch exposed power terminals, or inspect high-voltage connections for mains-powered beds.

  1. Power off and wait for cooling, then check if the thermistor is securely plugged in and if the wires are broken or shorted.
  2. Verify the thermistor model and pin configuration match the actual hardware.
  3. If necessary, temporarily relax the temperature range to observe reading changes, e.g., lower min_temp or raise max_temp.
  4. After identifying and resolving the wiring or configuration issue, immediately restore the original safe temperature limits.
  5. Save and restart Klipper.

Related configuration reference: Heating Related.

Heater not heating at expected rate​

Error Message: The heater is not heating up at the expected rate. Possible log messages include Heater extruder not heating at expected rate or Heater heater_bed not heating at expected rate.

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Common Causes:

  • Abnormal output from the heater cartridge, heated bed, or SSR/MOSFET.
  • Poor thermistor contact, partially broken wires, or fluctuating readings.
  • A fan blowing directly onto the hot end, heated bed, or heating area, causing slow temperature rise.
  • Insufficient heated bed power or max_power set too low.
  • Inappropriate PID parameters causing excessive fluctuation near the target temperature.

Solutions:

Power off

Before checking heaters, thermistors, heated beds, fuses, SSRs, MOSFETs, or power-related wiring, completely turn off the printer and disconnect the power supply. Allow the hot end and heated bed to cool. Do not disassemble the power supply, touch exposed terminals, or inspect high-voltage connections for mains-powered beds.

  1. Power off and wait for cooling, then check the heater and thermistor connections for tightness.
  2. Observe the temperature curve to see if heating is continuous and if there are abnormal fluctuations.
  3. Check if any fan is blowing directly onto the hot end or heated bed.
  4. For issues with SSRs, MOSFETs, power supply capacity, or high-voltage heated beds, regular users should prioritize checking the temperature curve in the web interface, replacing the module, or contacting after-sales service. Do not disassemble or perform electrical checks yourself.
  5. After confirming hardware is normal, re-run PID calibration.
  6. If the issue is confirmed to be slow heating due to a large heated bed or special structure, refer to verify_heater Optimization.

Related configuration reference: Heating Related, M109 Optimization.

Abnormal Temperature Readings (Displaying 0°C or Continuous Fluctuation)​

Error Message: Temperature displayed as 0°C, a negative value, or continuously fluctuating significantly (±10°C or more).

Common Causes:

  • Thermistor open circuit (displays 0 or very low value).
  • Thermistor short circuit (displays very high value or triggers ADC out of range).
  • sensor_type configuration does not match the actual thermistor model.
  • Missing pullup_resistor configuration for PT100 sensors.
  • Thermocouple signal interference requiring filter_length or thermocouple_max_error configuration.
  • ADC noise interference.

Solutions:

  1. Run QUERY_ADC SENSOR=extruder_temp to check the raw ADC reading.
  2. Run M105 to view the current temperature reading.
  3. Confirm sensor_type matches the hardware. Common types include NTC 100K beta 3950, PT100, MAX31865, etc.
  4. For PT100 sensors, check sensor_pin, rtd_reference_r, and rtd_num_of_wires.
  5. For thermocouples, check thermocouple_max_error. If ADC noise is high, check filter_length.

Related configuration reference: Heating Related.

MCU shutdown: Verify heater extruder/heater_bed​

Error Message: MCU 'mcu' shutdown: Verify heater extruder or Verify heater heater_bed.

Cause: Klipper's built-in verify_heater safety check detected that the heater temperature change did not meet expectations. This can be caused by abnormal heater output, unreliable thermistor readings, SSR response delays, or a mismatch between the heating curve of a high-power heated bed and the default detection parameters.

Note

Do not bypass the error by directly disabling the verify_heater function or setting its thresholds to extremely unreasonable values. This removes Klipper's last layer of safety verification for the heater and thermistor.

Common Scenarios:

  • Large heated bed + SSR: The SSR switching response, bed thermal mass, and default heating_gain do not match.
  • After replacing the heater cartridge, heated bed, or thermistor, the new hardware's thermal characteristics are incompatible with the old PID and verification parameters.
  • A fan blowing directly onto the hot end causes temperature fluctuations from ambient airflow that exceed the max_error range.
  • Poor thermistor contact or loose mounting causing intermittent readings.
  • Unstable power supply voltage or insufficient power supply capacity.

Troubleshooting Methods:

Power off

Before checking heaters, thermistors, SSRs, MOSFETs, fuses, or power-related wiring, completely turn off the printer and disconnect the power supply. Allow the hot end and heated bed to cool. Do not disassemble the power supply, touch exposed terminals, or inspect high-voltage connections for mains-powered beds.

  1. First, power off and check if the thermistor is securely plugged in and the heater wiring is tight.
  2. Observe the temperature curve in klippy.log leading up to the shutdown. If the curve is steadily rising without fluctuations, the parameters are likely too sensitive. If the curve shows intermittent jumps, drops to zero, or spikes, prioritize hardware issues.
  3. Check the [verify_heater extruder] or [verify_heater heater_bed] configuration section.
  4. After confirming hardware is normal, re-run PID calibration and observe if the false shutdowns still occur.
  5. For more detailed parameter explanations and tuning examples, refer to verify_heater Optimization.

HOST temperature above maximum temperature​

Error Message: HOST temperature xx above maximum temperature or MCU temperature not supported on xxx.

Common Causes:

  • The host computer's CPU temperature exceeds the max_temp defined in [temperature_host].
  • The mainboard MCU's built-in temperature sensor is not supported by the current firmware/chip.
  • Insufficient host cooling, e.g., enclosed case, stopped fan, or high ambient temperature.

Solutions:

  1. Check the host's heatsink, fan, and case ventilation.
  2. Use vcgencmd measure_temp, sensors, or system monitoring tools to view the CPU temperature.
  3. If the threshold is simply set too low, adjust [temperature_host] max_temp appropriately, but do not disable temperature protection.
  4. If the error is MCU temperature not supported, delete or comment out the [temperature_mcu] configuration for the unsupported MCU.

Related configuration reference: Fan Reference Configuration.

Extrusion Issues​

Extrude below minimum temp​

Error Message: Extrude below minimum temp or Extruder not hot enough in the log.

Solutions:

  1. Before extruding, ensure the nozzle has reached the required temperature for the filament.
  2. Check start G-code and macros like M600, PAUSE, RESUME for missing temperature wait commands.
  3. Use M109 or the Klipper equivalent wait command where temperature waiting is needed.
  4. Check the thermistor and temperature curve to confirm stable readings.
  5. It is not recommended to permanently lower min_extrude_temp to bypass this error.

Related configuration reference: M109 Optimization, Macros Introduction.

Extrude only move too long​

Error Message: Extrude only move too long (xxmm vs xxmm).

Solutions:

  1. Check the retraction length in the slicer. Do not set it excessively long, even for Bowden remote extruders.
  2. Break up long extrusion moves in filament change or load macros into multiple segments.
  3. Check the correct usage of M82/M83 and G92 E0 in macros.
  4. If a long extrusion is truly necessary, increase max_extrude_only_distance appropriately in [extruder].

Related configuration reference: Extruder Reference Configuration, Macros Introduction.

Move exceeds maximum extrusion​

Error Message: Move exceeds maximum extrusion (xxmm^2 vs xxmm^2).

Solutions:

  1. Check the slicer settings for abnormal filament diameter, nozzle diameter, extrusion multiplier, or line width.
  2. Check the extrusion mode and G92 E0 in start/pause/resume macros.
  3. Check nozzle_diameter, filament_diameter, or max_extrude_cross_section in [extruder].
  4. It is not recommended to significantly increase max_extrude_cross_section. First, verify the G-code and slicer parameters are correct.

Related configuration reference: Extruder Reference Configuration, Machine Calibration.

Extrude when no extruder present / Extruder not configured​

Error Message: Extrude when no extruder present, Extruder not configured, or Active extruder does not have a stepper.

Solutions:

  1. Confirm the main extruder configuration section is named [extruder].
  2. For multi-extruder or synchronized extrusion scenarios, check [extruder_stepper] and SYNC_EXTRUDER_MOTION.
  3. Check if ACTIVATE_EXTRUDER, T0/T1, or custom switching commands in macros point to a real configuration section.

Related configuration reference: Extruder Reference Configuration.

Filament Runout Detection and M600 Filament Change Errors​

Error Message: Filament sensor: runout detected, print interruption after M600 macro execution cannot be resumed, or the runout detection switch is permanently triggered or untriggered.

Solutions:

Power off

Before checking, unplugging, or replacing the filament runout sensor wiring, completely turn off the printer and disconnect the power supply. Do not plug/unplug the sensor module or arrange interface wiring while powered on.

  1. Run QUERY_FILAMENT_SENSOR SENSOR=<sensor_name>. Confirm the state is open (or not triggered) when filament is inserted, and changes when filament is removed.
  2. If the state does not change, power off and check the sensor wiring, switch_pin, and pull-up configuration.
  3. If there are frequent false triggers during printing, check if the wiring is excessively bent in the cable chain or pulled by moving axes.
  4. Check the M600 macro logic, ensuring the pause, retract, lift, and resume sequences are correct.
  5. For multi-extruder setups, confirm that ACTIVATE_EXTRUDER and the runout detection logic affect the same extruder.

Related configuration reference: Macros Introduction, Filament Switch Sensor Reference Configuration.

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