Kaeser rotary screw compressors are run by Sigma Control, and the fault language depends on the generation. First-generation Sigma Control, the green-keypad text-display unit on the AS, BS, CS, DS, ES and SK/SM/SX series from around 2000, shows short lower-case messages with a severity letter: ADT (A) for an airend discharge temperature trip, motor T (A) for a hot drive motor, separator dp (W) for a clogging separator. Sigma Control 2, the industrial-PC controller with RFID access on ASD, BSD, CSD, DSD, ESD and related machines built since about 2011, uses a four-digit number plus a letter, with arrows marking whether the value went over or under its limit.
How to read the display. The letter is the severity. A is an alarm: the controller has shut the machine down to protect it, and it stays down until the cause is fixed and the message is acknowledged with the reset key. W is a warning or service reminder the machine keeps running through. The number alone is not enough, because the same number can exist with both letters and mean different things: 0013 A is a motor overcurrent shutdown, 0013 W means change the air filter. The same subsystem often has a W code that comes before its A code, so 0004 W (oil separator differential pressure rising) is your early notice of 0022 A (oil separator clogged, shutdown), and 0008 W (airend temperature approaching the limit) is the warning before 0015 A, the overheat trip. Two quirks are worth knowing: the message numbers are not consecutive, and the exact set varies with how the machine is equipped, so a number you have never seen is an option your machine has that another does not. Original Sigma Control machines also enforce a minimum start temperature of +3 °C, so a winter no-start in an unheated room is often the controller doing its job.
What is safe to do yourself. Kaeser's manuals are unusually explicit about which remedies belong to operators (cleaning coolers, checking oil level after cooldown, replacing air filters) and which require the machine depressurised and a trained technician (anything inside the separator tank or the electrical cabinet). The pages below preserve that line.
The tables below list every documented message by controller generation. Each links to its own page with the meaning, the machines that show it, the likely causes, the operator checks, and the handoff point to a technician. Each page cites the Kaeser service manual it was verified against.
Five Kaeser codes to know first
- 0015 A — Airend discharge temperature ADT ⇞ (Kaeser Sigma Control 2): Airend discharge temperature too high (shutdown).
- 0013 W — Air filter Δp ↑ - Change air filter! (Kaeser Sigma Control 2): Air filter clogged.
- 0022 A — Oil separator Δp ⇞ (Kaeser Sigma Control 2): Oil separator cartridge clogged (shutdown).
- 0004 A — EMERGENCY STOP (Kaeser Sigma Control 2): Emergency stop button pressed.
- ADT (A) (Kaeser Sigma Control (original)): Airend discharge temperature exceeded (original Sigma Control).