---
tag: m0109
title: Wait for Hotend Temperature
brief: Wait for the hot end to reach its target.
author: thinkyhead

group: thermal

codes: [ M109 ]

notes:
  - With `PRINTJOB_TIMER_AUTOSTART` this command will start the print job if heating, and stop the print job timer if the temperature is set at or below half of `EXTRUDE_MINTEMP`.
  - This command (as well as [`M190`](/docs/gcode/M190.html)) can block new commands from the host, preventing remote shutdown. However, if `EMERGENCY_PARSER` is enabled, a host can send [`M108`](/docs/gcode/M108.html) to break out of the wait loop.
  - To set the hot end temperature and proceed without waiting, use [`M104`](/docs/gcode/M104.html).

parameters:
  -
    tag: I
    since: 2.0.6
    optional: true
    description: Material preset index. Overrides `S`.
    values:
      -
        type: int
        tag: index
  -
    tag: S
    optional: true
    description: 'Target temperature (wait only when heating). Also `AUTOTEMP`: The min auto-temperature.'
    values:
      -
        tag: temp
        type: float
  -
    tag: R
    optional: true
    description: Target temperature (wait for cooling or heating).
    values:
      -
        tag: temp
        type: float
  -
    tag: F
    optional: true
    description: Autotemp flag. Omit to disable autotemp.
    values:
      -
        tag: flag
        type: bool
  -
    tag: B
    optional: true
    description: With `AUTOTEMP`, the max auto-temperature.
    values:
      -
        tag: temp
        type: float
  -
    tag: T
    optional: true
    description: Hotend index. If omitted, the currently active hotend will be used.
    values:
      -
        tag: index
        type: int


examples:
  -
    pre: Set target temperature and wait (if heating up)
    code: M109 S180
  -
    pre: Set target temperature, wait even if cooling
    code: M109 R120
  -
    pre: Set target temperature for E1 and wait (if heating up)
    code: M109 T1 R205
  -
    pre: '`AUTOTEMP`: Set autotemp range, wait for temp'
    code: M109 F S180 B190
  -
    pre: '`AUTOTEMP`: Disable autotemp, wait for temp'
    code: M109

---

This command optionally sets a new target hot end temperature and waits for the target temperature to be reached before proceeding. If the temperature is set with `S` then [`M109`](/docs/gcode/M109.html) waits *only when heating*. If the temperature is set with `R` then [`M109`](/docs/gcode/M109.html) will also wait for the temperature to go down.