1
First check 1
Drive won't start
Check STO chain and control permissions first.
Signals to confirm
Enable wiringPower stageSafe torque off
Next move
Use the code browser below to confirm the closest fault code.
Error system hub
Siemens S120 Error Codes
Complete error code reference for the SINAMICS S120 modular drive system. Includes root-cause hints and quick diagnostics.
Critical
2
Warning
1
Info
0
Understand this system
Use this section to confirm what this error system covers, which device families it typically appears in, and how the main fault families are grouped before you move into individual codes.
Common fault families
Thermal
2 codes indexed under thermal diagnostics.
Power Supply
1 code indexed under power supply diagnostics.
First checks before code lookup
Use these system-level checks first when the exact code is not yet confirmed. The goal is to narrow the failure path before you open a specific code page.
2
First check 2
Motor runs hot
Verify thermal model and switching frequency.
Signals to confirm
Load profileCooling fan statusMotor data
Next move
Use the code browser below to confirm the closest fault code.
3
First check 3
Drive trips during acceleration
Increase acceleration time and inspect mechanics.
Signals to confirm
Ramp settingsCurrent limitLoad inertia
Next move
Use the code browser below to confirm the closest fault code.
4
First check 4
Drive trips during deceleration
Validate braking unit capacity and thresholds.
Signals to confirm
Braking resistorDC overvoltageRegen energy
Next move
Use the code browser below to confirm the closest fault code.
Common fault groups
These groups help you translate a broad symptom into a smaller fault family, then move into the closest representative codes.
Fault group
Thermal
2 codes indexed under thermal diagnostics.
Start with these codes
Fault group
Power Supply
1 code indexed under power supply diagnostics.
Start with these codes
Start with these codes
Use these curated entry points when you need a fast shortlist before working through the full code browser.
Common codes to start with
Use these as the fastest entry points when the system has not yet been narrowed to a single failure path.
Priority codes to review first
These codes usually deserve faster attention because they are more disruptive or more likely to hide upstream system issues.
Browse all codes in this system
Use search, category filters, and severity filters to narrow the closest codes in this system once the first checks above are complete.
3 codes availableUpdated: 2026-03-01
CodeSeverityDescription
Guides, tools, and next steps
Use these guides, tools, and reference materials once the fault path is narrowed and you need to verify the next move.
Frequently asked questions
These answers cover the system-level questions that usually come up before or during code-by-code troubleshooting.
Next step
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