Siemens SINAMICS drives are the backbone of European and American industrial automation — from the compact V20 to the modular S120 multi-axis system. When a SINAMICS drive shows an F-code (fault) or A-code (alarm) on the BOP or IOP display, understanding the root cause is essential to minimizing downtime. This guide covers the most common SINAMICS fault codes across the G120, G120C, S120, and V20 families.
How SINAMICS Fault Codes Work
Siemens uses a standardized numbering system across all SINAMICS platforms:
- Fxxxxx — Faults: Drive stops immediately. Must be acknowledged (reset) after the cause is resolved.
- Axxxxx — Alarms: Warning conditions. Drive continues running but may reduce performance.
Faults are displayed on the BOP (Basic Operator Panel), IOP (Intelligent Operator Panel), or read via PROFINET/PROFIBUS using parameter r0945 (fault code) and r0949 (fault value).
Critical SINAMICS Fault Codes
F001 — Overcurrent
Affected drives: G120, G120C, V20, S120
What it means: The drive measured output current exceeding the maximum permissible limit.
Common causes:
- Short circuit in motor cable or motor windings
- Motor rated current significantly exceeds drive rated current
- Sudden mechanical jam or seizure
- IGBT module failure — shorted output transistor
Troubleshoot: Disconnect motor cables and reset. If fault clears, check motor insulation (megger test >5 MΩ). If fault persists with no load, the drive has internal IGBT damage. Send for repair.
F004 — Overvoltage DC Link
What it means: The DC bus voltage exceeded the maximum threshold (typically 410V DC for 230V drives, 820V DC for 400V drives).
Common causes:
- Motor decelerating too fast — regenerative energy feeding back to DC bus
- Incoming supply voltage too high
- Missing or undersized braking resistor
- Failed braking chopper IGBT
Fix: Increase deceleration ramp time (P1121). If using a braking resistor, verify it's connected and the correct resistance value. Check incoming voltage — should be within ±10% of nominal.
F005 — Undervoltage DC Link
What it means: DC bus voltage dropped below minimum threshold.
Common causes:
- Power supply interruption or voltage sag
- Loose incoming power connections
- DC bus capacitors degraded — can't hold voltage during brief sags
- Rectifier bridge failure
Troubleshoot: Measure incoming voltage at drive terminals under load. If voltage is stable but fault persists, the DC bus capacitors or rectifier are failing — component-level repair needed.
F011 — Motor Overtemperature
What it means: The motor temperature sensor (PTC, KTY, or Pt1000) reported temperature exceeding the configured threshold (P0604).
Common causes:
- Motor running above rated current for extended periods
- Blocked motor ventilation or failed cooling fan
- Ambient temperature too high
- Faulty temperature sensor or wiring
Fix: Check motor cooling fan operation. Verify motor is not mechanically overloaded. If the sensor reads open circuit or short circuit, replace the sensor or repair the wiring — this is not a drive issue.
F030 — Power Unit Failure
What it means: The power module reported an internal hardware failure to the control unit. This is a critical fault.
Common causes:
- IGBT desaturation — the output transistor is failing to switch properly
- Gate driver board failure
- Power module overtemperature (internal sensor)
- Firmware/hardware mismatch after partial component replacement
This fault always requires professional repair. The power module needs component-level diagnosis. Learn about Siemens repair at Flexa Systems.
F035 — Fan Failure
What it means: The drive's internal cooling fan is not running or running below minimum speed.
Common causes:
- Fan motor burned out
- Fan bearing seized (common after 3–5 years)
- Fan power supply circuit on the control board failed
Fix: Replace the cooling fan. Siemens fan modules are usually plug-and-play on G120 frame sizes A–F. If the fan is good but the fault persists, the fan monitoring circuit on the control board is damaged.
F040 — Motor Auto-Tuning Failed
What it means: The motor identification/auto-tuning routine (P1910) could not complete successfully.
Common causes:
- Motor not connected or cables disconnected
- Motor nameplate data (P0304–P0311) entered incorrectly
- Mechanical load preventing free rotation during rotating measurement
- Output contactor between drive and motor
Fix: Verify motor connections. Enter correct nameplate data. If using a stationary measurement (P1910=1), ensure no output contactor. For rotating measurement (P1910=3), decouple the load if possible.
F052 — EEPROM Fault
What it means: The drive's parameter memory (EEPROM) has a read/write error.
Common causes:
- EEPROM chip end of life (limited write cycles)
- Power interruption during parameter save
- Board-level component failure
This requires board-level repair. Factory reset (P0010=30) may temporarily work, but the EEPROM will fail again. Send for professional repair.
SINAMICS Fault Code Quick Reference Table
| Code | Name | Severity | Typical Cause | DIY or Repair? |
|---|---|---|---|---|
| F001 | Overcurrent | Critical | Short circuit / IGBT | Megger motor; if OK → Repair |
| F004 | DC Overvoltage | Medium | Decel too fast / braking | DIY — increase ramp |
| F005 | DC Undervoltage | Medium | Power loss / capacitors | Check supply; if stable → Repair |
| F011 | Motor Overtemp | Medium | Cooling / overload | DIY — check fan & load |
| F030 | Power Unit Fail | Critical | IGBT / gate driver | Repair |
| F035 | Fan Failure | Low | Fan motor / bearing | DIY — replace fan |
| F040 | Auto-Tune Failed | Low | Wrong data / load coupled | DIY — re-enter parameters |
| F052 | EEPROM Fault | High | Memory chip failure | Repair |
When to Troubleshoot vs. When to Send for Repair
Fix these yourself: F004 (ramp time), F011 (cooling/load), F035 (replace fan), F040 (re-tune)
These need component-level repair: F001 with good motor (IGBT), F005 with stable power (capacitors), F030 (power module), F052 (EEPROM)
Siemens SINAMICS Repair at Flexa Systems
We repair all SINAMICS platforms — G120, G120C, G130, G150, S120, S150, V20, and legacy MicroMaster 420/430/440. Component-level repair on power modules, control units, and communication boards.
- Free diagnostic evaluation
- 2-year warranty on all repairs
- 5–10 business day standard turnaround
- Rush 24–72h available
Request your free SINAMICS evaluation →