Kaeser Compressor Fault Codes - SIGMA Control Alarms

Kaeser Compressor Fault Codes - SIGMA Control 2 Quick Reference

Kaeser screw compressors with SIGMA Control and SIGMA CONTROL 2 controllers report warnings and shutdowns for temperature, pressure, service intervals, and sensor faults. The controller panel may show text alarms rather than short numeric codes, depending on generation. If you searched for “Kaeser compressor fault code 2,” confirm whether the machine has the SIGMA CONTROL 2 controller, then use the alarm text on the display.

Kaeser deliberately favors descriptive alarm text over a short numeric code list, because a single number cannot capture the difference between a shutdown that stops the compressor immediately and a warning that only flags upcoming maintenance. Read the full message on the display before touching anything. The table below groups the alarm families you will actually see across SIGMA Control and SIGMA CONTROL 2 packages, in rough order of how often each one shows up in the field.

Tools You Will Need

• Digital multimeter with AC voltage and resistance ranges, plus a clamp meter for motor amp draw
• Mechanical pressure gauge to cross-check the controller’s transducer reading
• Non-contact infrared thermometer for verifying final compression and cooler surface temperatures
• Compressed air or a soft brush for cleaning cooler fins without bending them
• The compressor’s SIGMA Control manual with the alarm text list for the exact controller generation
• Kaeser-approved oil and the correct service kit part number for the package model

Safety Before You Start

Lock out and tag out the compressor’s main disconnect before opening any electrical enclosure, and verify zero voltage with a meter rather than trusting the disconnect position alone. These machines run on three-phase power at industrial voltages, so treat every terminal as live until you confirm otherwise. The compressed air receiver and discharge piping hold stored pressure even after the motor stops, so bleed the system down through the proper drain or relief point before opening any fitting, filter housing, or separator. The airend and drive motor retain rotational energy briefly after shutdown, and cooling surfaces stay hot for some time after a hard stop, so let the package cool before reaching into the cabinet. Never bypass a safety interlock or E-stop circuit to keep a machine running through an active fault.

Most Common Faults

Final Compression Temperature High

Kaeser packages are efficient, but they still depend on clean cooling surfaces and correct oil flow. Blow out coolers, verify cabinet fans run properly, and confirm the oil level is correct with the unit in the proper state per Kaeser instructions.

Sensor Fault

Before replacing expensive valves or motors, compare the controller reading to an independent gauge or temperature probe. Kaeser sensor failures are common enough that a bad sensor should always be on the suspect list.

Dryer Fault

If the package has an integrated refrigerated dryer, the dryer can trip independently of the compressor. Check condenser cleanliness, ambient temperature, and whether the dryer fan is running.

Motor Protection Trip

A motor protection trip means the overload relay or motor protection module in the controller measured current or thermal conditions outside the safe range for the main drive motor. Check for a mechanically bound airend, a failed bearing causing excess load, or a loose or corroded power connection creating unbalanced phase current. Confirm the overload setting matches the motor’s actual full-load amp rating on the nameplate before assuming the motor itself has failed.

Phase Fault

A phase fault trips when the controller detects missing, reversed, or badly unbalanced three-phase supply voltage. Measure voltage between all three phase legs at the incoming disconnect with a multimeter. A voltage imbalance greater than a few percent between legs, or a completely missing leg, points to a supply-side problem such as a blown fuse, a loose connection upstream, or a utility issue rather than a compressor fault.

Emergency Stop Active

An E-stop alarm means a physical stop button or an interlocked door/guard switch somewhere in the loop is open. Trace the full E-stop circuit rather than assuming the button itself is the problem, since these circuits are often wired in series through multiple guards, doors, and remote stop stations. A single open contact anywhere in that chain will hold the whole loop in a faulted state.

Step-by-Step Diagnostic Sequence

1. Read the full alarm text on the display and note whether the controller classifies it as a warning (compressor keeps running) or a shutdown (compressor stops), since that distinction changes how urgently you need to respond.
2. Check the alarm and event history in the SIGMA Control menu to see whether this is a first occurrence or a recurring trip, and note the operating hours and conditions logged at the time of the fault.
3. Confirm cooling airflow and ambient conditions around the package, since restricted airflow into or out of the cabinet is the single most common root cause behind temperature, dryer, and even some motor protection alarms.
4. Cross-check any sensor-reported value (temperature or pressure) against an independent gauge or thermometer before trusting the controller’s number or condemning the sensor.
5. Verify supply power quality with a multimeter if the fault involves phase, motor protection, or intermittent shutdowns, since unstable incoming power causes symptoms that look mechanical but are actually electrical.
6. Match the alarm to the specific section above and work through that fault’s checks in order rather than replacing parts speculatively.
7. Reset the fault only after correcting the underlying cause, then run the compressor under load and monitor the same reading for at least one full duty cycle to confirm the fix held.

Parts Often Needed

SIGMA CONTROL 2 Notes

For second-generation controllers, use the Kaeser SIGMA CONTROL 2 fault-code guide to separate shutdown, warning, and maintenance messages before ordering parts. That page covers final compression temperature, dryer faults, service required, pressure sensors, differential pressure, communication faults, and phase alarms in more detail. If your display shows a menu path or icon layout that does not match either controller generation described here, check the compressor’s nameplate and control panel data plate for the exact controller model before assuming which alarm list applies.

Focused Parts Searches

Before ordering, match the compressor part to the package model, controller generation, electrical rating, and failure symptom.

• Kaeser compressor temperature sensor
• Kaeser compressor pressure transducer
• Kaeser compressor service kit
• Kaeser compressor cabinet cooling fan
• Kaeser dryer condenser fan

When to Call a Pro

Kaeser Sigma Control diagnostics are much easier with factory documentation and service access. If alarms persist after PM work, involve a Kaeser-trained compressor tech before the airend is damaged. Any fault that involves opening the compressed air circuit under pressure, working inside the drive motor terminal box, or repeated final compression temperature trips after a full cooler cleaning and oil check should go to a qualified technician rather than continued self-diagnosis, since airend damage from running through a genuine overheat condition is far more expensive than a service call.

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