QIDI Q1 Pro: errors «Probe samples exceed samples_tolerance», «ADC out of range» or «MCU MKS_THR»
Guide based on the manufacturer's official documentation; usi3d has not yet verified it on a machine.
Technology: FDM · Brand: Qidi · Symptoms: The printer shows an error code or message, Temperature error (MINTEMP, MAXTEMP, thermal runaway), Unlevel or warped bed · Updated on 9 October 2026
Symptom
The Q1 Pro stops and shows a Klipper message on screen such as «!!Probe samples exceed samples_tolerance, probe failed» when levelling, «Mcu mcu shutdown: Thermocouple ADC out of range», «Heater extruder not heating at expected rate» or «Lost communication with MCU MKS_THR».
Likely causes, from most to least likely
- Probe failed: the PEI plate is not placed correctly and this affects the bed pressure sensor.
- Thermocouple ADC out of range: the hotend thermocouple has failed.
- Heater extruder not heating at expected rate: the hotend has failed or, if the error persists with another hotend, the adapter board.
- Lost communication with MCU MKS_THR: almost always the printhead (Type-C) cable or the adapter board.
Checks to tell which one it is
- Check that the PEI plate is properly seated on the bed with nothing underneath.
- Write down the exact message: each one points to a different part.
- If you have another hotend, try it: if the error does not appear with it, the problem is the hotend.
Before you start
Before taking anything apart, cleaning or adjusting it, switch the printer off and unplug it, unless a step says otherwise, and do not touch the nozzle, the heater block or the bed until they have cooled down. If in any doubt about electricity, heat or moving parts, stop and ask a professional.
Step-by-step fix
Probe failed: seat the plate properly
Remove the PEI plate and put it back properly seated. Repeat levelling.
Check: Levelling completes without the samples_tolerance message.
If that does not fix it: Contact QIDI after-sales service.
Heater extruder: try another hotend
With the printer off and cold, swap the hotend for another one. If the other one works, ask QIDI for a new hotend; if the error appears with both, the fault is in the adapter board and QIDI needs to send one.
Check: The nozzle heats without the error.
If that does not fix it: Contact QIDI after-sales service.
Thermocouple ADC out of range
QIDI says to replace the thermocouple or the whole hotend. Do it with the printer off and the hotend cold, and wear heat-resistant gloves if you need to heat it to loosen the nozzle.
Check: The hotend temperature reads correctly and the warning does not return.
If that does not fix it: Contact QIDI after-sales service.
Lost communication with MCU MKS_THR
According to QIDI, most cases are solved by replacing the printhead Type-C cable or the adapter board. Replace the cable first, with the printer off.
Check: Klipper starts without losing communication with the printhead.
If that does not fix it: Ask QIDI for the adapter board.
Prevention
- Always seat the PEI plate properly before levelling.
- Only swap the hotend with the printer off and cold.
- When refitting the printhead, do not force or bend the Type-C cable.
Still not fixed?
Tell usi3d's AI about your case: choose your printer, describe what you see and add photos if you like. It proposes checks step by step, with their sources.
Printers it applies to
Qidi Q1 Pro.
Official sources
This guide summarises the official documentation linked here:
This guide is general information: usi3d has summarised it from the official documentation linked here, and it may not match your model, its version or its firmware. If in doubt, follow the manual and the support of your printer's manufacturer. You decide what you do with your machine, and working on it may affect its warranty.