What does Kaeser alarm 0041 A (mains voltage too low) mean?
Short answer: Power supply failure (second occurrence). If your Kaeser Sigma Control 2 is showing 0041 A — Mains voltage ⇟, the controller has logged a specific, documented condition. This page covers what it means, what causes it, what you can safely fix yourself, and when — and why — it takes a technician.
What exactly is the machine telling you?
A second power failure occurred and the machine shut down. The manual points to the supply voltage and the door interlock switch circuit.
Which machines show this?
the wide range of current-generation Kaeser rotary screw compressors — ASD, BSD, CSD, DSD, ESD and related series — built since roughly 2011 with the Sigma Control 2, the industrial-PC controller with a text display and RFID access. It reports faults as a four-digit number plus a letter: 'A' messages are alarms that shut the machine down, 'W' messages are warnings or service reminders it keeps running through, with arrows marking whether the value went over or under its limit — so 0015 A is the airend-overheat shutdown while 0013 W just asks for an air filter. Practical tip: the same subsystem often has a W and an A code (0004 W before 0022 A on the separator); acting on the W message is how you avoid the A shutdown.
What causes it?
- A second facility power failure or brownout
- An enclosure door not fully closed, opening the interlock circuit
Can you fix it yourself?
Usually, yes — confirm the facility power event, close all doors properly, acknowledge, and restart once power is stable.
Step by step — what to try, in order:
- Check whether the facility had a brownout or power interruption.
- Confirm all enclosure doors are fully closed (interlock switch contact).
- Acknowledge and restart once power is stable.
When do you need a technician — and why?
Repeated alarms on stable power mean the supply or interlock circuit needs an electrician or Kaeser service to test — intermittent control-power faults don't find themselves.
If it does come to a service call and you're in Nashville, TN or Birmingham, AL, we maintain independently compiled lists of local companies that service industrial air compressors — real businesses with verified contact information, none of whom paid to be listed.
Related questions
What does 0041 A — Mains voltage ⇟ mean on a Kaeser Sigma Control 2?
Power supply failure (second occurrence). A second power failure occurred and the machine shut down. The manual points to the supply voltage and the door interlock switch circuit.
Can I fix 0041 A — Mains voltage ⇟ on a Kaeser Sigma Control 2 myself?
Usually, yes — confirm the facility power event, close all doors properly, acknowledge, and restart once power is stable.
When does 0041 A — Mains voltage ⇟ on a Kaeser Sigma Control 2 need a technician?
Repeated alarms on stable power mean the supply or interlock circuit needs an electrician or Kaeser service to test — intermittent control-power faults don't find themselves. If power is stable and the alarm repeats, have an electrician or Kaeser service check the supply and interlock circuit.
Verified against service documentation: Kaeser Sigma Control 2 documentation for 0041 A — Mains voltage ⇟ (airsolcan.com)