Heater Fault at Print Start

A heater fault during print startup means one of the printer's heaters (bed, chamber, or nozzle) triggered a fault before the actual print began – during the preheat, chamber heating, or heat soak phase in initial.g. The print is cancelled and never starts. This is different from a heater fault during printing. During print startup the printer runs a specific heating sequence with diagnostic logging that helps pinpoint the cause.

Why This Happens

The firmware monitors all four heaters (H0: left nozzle, H1: right nozzle, H2: bed, H3: chamber) during the entire startup sequence. If any heater cannot reach or maintain its target temperature within the allowed time and tolerance, the firmware triggers a fault, cancels the print, and saves diagnostic files.

Common Causes

HEPA fan cooling the bed (most common)

The Vision Miner 22IDEX V4 has a powerful HEPA filtration fan that circulates air through the chamber. At high bed target temperatures (above 140 °C), the HEPA fan's airflow can cool the build plate faster than the heater can compensate – causing the bed heater to fault.

This is a known issue. The fix is a firmware update that introduces a three-tier HEPA management strategy during print startup:

Other possible causes:

• Slow heating – Poor bed insulation, damaged heater wiring, or a degraded heater element. The heater cannot raise temperature fast enough to satisfy the fault detection timeout.
• Temperature sensor issues – Loose or damaged thermistor/PT1000 connection causing erratic readings. The firmware sees sudden temperature drops and faults.
• PSU voltage drop – Insufficient or unstable power supply voltage. When multiple heaters activate simultaneously, voltage drops can reduce heater output. Check board voltages in the diagnostic TXT file (see below).
• Incorrect PID parameters – Custom or corrupted PID tuning values can cause temperature oscillations large enough to trigger a fault. Re-run PID tuning from Macros → System → Calibration → Temperature Tuning.
• Aggressive M570 settings – If someone manually tightened the fault detection parameters (M570), the heater may fault under normal conditions. The defaults are:
  • Bed (H2): M570 H2 P60 T50 R5 – 60-second monitoring period, 50 °C tolerance
  • Chamber (H3): M570 H3 P600 T70 R5 – 600-second monitoring period, 70 °C tolerance

Diagnostic Files

Starting with the latest firmware, the printer automatically logs temperatures and heater parameters during every print startup. If a heater fault occurs, two diagnostic files are saved to the SD card. If heating succeeds, the files are automatically deleted.

File Location

0:/sys/Result/print_start_log.csv
0:/sys/Result/print_start_log.txt

CSV File – Temperature Log

Logged every 10 seconds during bed heating, chamber heating, and heat soak. Each row contains:

The last line of the CSV indicates when the fault occurred:

• RESULT: FAILED - Heater fault during bed heating
• RESULT: FAILED - Heater fault during chamber heating
• RESULT: FAILED - Heater fault during heat soak

TXT File – Configuration Snapshot

A full snapshot of heater configuration at print start:

• Target temperatures for all tools, bed, and chamber
• M307 heater model parameters (heating rate, cooling rate, dead time) for each heater
• PID values (P, I, D) for each heater
• M570 fault detection settings (monitoring period, temperature tolerance, max bad readings)
• Heater monitors (temperature limits, actions)
• Average PWM for each heater
• Board voltages (current, min, max) for both boards
• MCU temperatures for both boards
• Firmware versions

How to Retrieve Diagnostic Files

1. Open the Web Interface in your browser.

2. Navigate to System in the file manager.

3. Open the Result folder.

4. Download print_start_log.csv and print_start_log.txt.

5. Send both files to Vision Miner support.

Running the Heating Test

If the fault is intermittent or you want to test heating performance independently, use the built-in Heating Test macro. This test runs outside of a print job and produces its own detailed log files.

1. Open the Web Interface.

2. Navigate to Macros → System → Troubleshooting → Heating Test.

3. Select which heaters to test: Both (Bed + Chamber) is recommended.

4. Choose the build plate target temperature (default: 160 °C).

5. Set the build plate Z position for the test (default: 100 mm).

6. The test will heat the selected heaters and log temperatures every 10 seconds.

The test creates its own log files in 0:/sys/Result/:

• heating_test_<timestamp>.csv – temperature log
• heating_test_<timestamp>.txt – heater configuration snapshot

If a fault occurs during the test, it is reported on screen and logged. Download the files and send them to support.

Auto-Shutdown After Heater Fault

The printer can be configured to automatically shut down when a heater fault is detected. This is useful for unattended operation.

To configure auto-shutdown:

1. Open the Web Interface.

2. Navigate to Macros → System → Settings → Faults.

3. Run Action After Heater Fault.

4. Select an option:
   • Disable – Fault displays a warning, printer stays powered on (default).
   • Immediate (0 s) – Printer shuts down immediately on fault.
   • Delay 30 / 60 / 120 s – Printer shows a countdown, then shuts down. You can cancel during the countdown.
   • Custom Duration – Enter a custom delay in seconds.

When a heater fault occurs:

• The LEDs flash red.

• If auto-shutdown is enabled, a countdown dialog appears. Press Keep power on to cancel the shutdown.

• If the countdown expires or Shut down now is pressed, the printer powers off completely.

FAQ

Support

If you could not find an answer here, reach out to our support team.