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Growatt Error 404: DC Bus Sampling Fault

Updated June 2026 · Reviewed for technical accuracy · ~2 min read

Error 404 is an internal "bus sampling" fault: the Growatt could not correctly read its own DC bus, the internal voltage rail between the panels and the AC output. This is internal to the inverter, so beyond a restart it is a matter for Growatt or your installer.

What it usually means

  • A transient sampling glitch a restart clears.
  • An internal measurement or board fault if it keeps returning.

What to do

  1. Power-cycle the inverter. AC breaker off, then the DC isolator, wait 5 minutes, restart. A one-off Error 404 may clear.
  2. If it returns, contact your installer or Growatt with the code and model. A persistent bus sampling fault is an internal hardware issue.

Related Growatt codes

Error 409, DC bus overvoltage Error 100, Voltage failure Error 116, EEPROM

Sources

  • Growatt inverter user manual and error-code reference (Error 404 = bus sampling fault; restart, contact Growatt if it persists).
  • Growatt installer documentation.
⚠️ Safety disclaimer. Solar inverters carry lethal DC and AC voltage even when "off". This guide covers a single safe power cycle only. Internal faults must be handled by a licensed installer or Growatt technician.