What does Kaeser alarm 0004 A (emergency stop) mean?
Short answer: Emergency stop button pressed. If your Kaeser Sigma Control 2 is showing 0004 A — EMERGENCY STOP, 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?
The EMERGENCY STOP push button is latched in. The machine cannot run until it is released.
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?
- The EMERGENCY STOP button is latched in — it must be physically released
- The button or its circuit faulty if the alarm survives release
Can you fix it yourself?
Yes — confirm the machine is safe, unlatch the button, and acknowledge with the reset key. That is the complete normal procedure.
Step by step — what to try, in order:
- Confirm the reason it was pressed has been resolved and the machine is safe.
- Unlock (unlatch) the emergency stop push button.
- Acknowledge the alarm with the reset key on the controller.
When do you need a technician — and why?
An alarm that stays active with the button released means the stop circuit is faulty, and a safety circuit must be repaired by service, not worked around.
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 0004 A — EMERGENCY STOP mean on a Kaeser Sigma Control 2?
Emergency stop button pressed. The EMERGENCY STOP push button is latched in. The machine cannot run until it is released.
Can I fix 0004 A — EMERGENCY STOP on a Kaeser Sigma Control 2 myself?
Yes — confirm the machine is safe, unlatch the button, and acknowledge with the reset key. That is the complete normal procedure.
When does 0004 A — EMERGENCY STOP on a Kaeser Sigma Control 2 need a technician?
An alarm that stays active with the button released means the stop circuit is faulty, and a safety circuit must be repaired by service, not worked around. If the alarm stays active with the button released, call service — the button or its circuit may be faulty.
Verified against service documentation: Kaeser Sigma Control 2 documentation for 0004 A — EMERGENCY STOP (airsolcan.com)