How do you read the fault codes on your air compressor's controller?

The first thing a compressor tech asks on the phone is some version of "what does the screen say?" — and the answer depends entirely on which controller your machine carries. Each of the six brands covered here speaks its own language. Here's how to identify yours and read it.

Atlas Copco — Elektronikon

Atlas Copco GA-series machines carry the Elektronikon family: the older Elektronikon II with a small text display, the Mk 5, and the current Elektronikon Touch. Faults appear as named conditions — the sensor name plus a state like Shd (shutdown) or Shdw (shutdown warning), and messages like *Serv Requir*. VSD machines add converter alarm codes (hex codes like 0x1111) and F-codes for drive faults. Nominal trip points: element outlet warning around 110°C, shutdown around 120°C. Full Atlas Copco code list →

Gardner Denver — AirSmart and AirSmart G2

Gardner Denver machines with the AirSmart controller report numbered messages in two groups: SHUTDOWN codes such as #101 FAN FAULT, #128 HIGH DISCH TEMP and #202 CHANGE SEPARATOR, which stop the compressor, and ADVISORY codes in the 300s such as #301 CHANGE SEPARATOR and #316 HIGH DISCH TEMP, which warn while it keeps running. The two stages line up: airend discharge temperature raises advisory #316 at 225°F (107°C) and shutdown #128 at 240°F (116°C). The newer AirSmart G2 spells its messages out in text instead: High Discharge Temp, Change Separator, Separator Change Timer. Full Gardner Denver code list →

Ingersoll Rand — Intellisys and Xe-series

Older SSR machines with Intellisys panels show numbered messages: -02- motor overload, -03- high discharge temperature, -07- emergency stop, and so on. Later SG-era controllers spell faults out in text (HIGH AIREND TEMPERATURE, CHECK MOTOR ROTATION). Current machines carry Xe-series controllers with structured codes: A: prefixes are alarms/warnings the machine keeps running through, E: prefixes are trips that shut it down — E:0010 is the emergency stop, E:0129 the excess temperature shutdown. Full Ingersoll Rand code list →

Kaeser — Sigma Control

Kaeser machines run Sigma Control (first generation, text messages like ADT) or Sigma Control 2, which uses numbered messages with a suffix: A for alarm shutdowns, W for warnings — 0015 A is the airend discharge temperature shutdown, 0013 W the air filter warning. One Kaeser quirk worth knowing: message numbers are not consecutive and the exact set varies with the machine's equipment, so don't panic if your neighbor's machine shows numbers yours never will. Full Kaeser code list →

Quincy — QSI, INFOLOGIC and Airlogic2

Quincy uses three different controllers. QSI-series machines with QSI standard controls show short text messages: HIGH TEMP, OVERLOAD, H.A.P. SHDN (high air pressure shutdown), and TEMP FAULT or PRES FAULT for a failed sensor. QGS 20-30 machines carry the INFOLOGIC controller, which talks in pictographs and LEDs instead of words: a flashing temperature pictograph is the element outlet warning at 105°C (221°F), a flashing alarm LED goes with shutdowns such as the element outlet trip at 110°C (230°F), and the service pictograph with screen d.06 means maintenance is due. QGD 40-60 and QGS 40-100 machines use Airlogic2, where a lit alarm LED means a warning and a flashing one means a shutdown; element outlet temperature warns at a factory setting of 113°C (235°F) and shuts down at 120°C (248°F). Full Quincy code list →

Sullair — Touch Screen, WS, Supervisor, ShopTek

Sullair has used several controllers: the current Sullair Touch Screen (STS), the WS controller, the Supervisor (which also relays VSD drive fault numbers), and ShopTek panels on smaller machines. Faults are mostly plain text — HIGH DISCH TEMP, MOTOR OVERLOAD, PR XDCR FAULT — with consistent thresholds across the line: warnings around 225°F discharge temperature, faults at 235-255°F, separator dP warnings around 10 psid. Full Sullair code list →

The three-step move when any of them trips

1. Photograph the display. The exact message, plus any values shown, before anything gets reset.
2. Look the code up on the brand pages above. It tells you whether you're looking at a cleaning problem, an electrical problem, or a stop-now problem.
3. Reset once, at most — after addressing what the code points at. A fault that returns after one reset is real, and repeated hot restarts are how airends die.

If the code points past in-house fixes and you're in our test markets, the verified service company lists for Nashville and Birmingham cover factory branches, authorized distributors, and independents.