What does Kaeser warning 0028 W (air filter service due) mean?
Short answer: Air filter maintenance interval expired. If your Kaeser Sigma Control 2 is showing 0028 W — Air filter h ⇞, 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 service-hour interval for the air filter has expired; replace the air filter.
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 air filter's service-hour interval has expired
- Filter due for replacement regardless of visible condition
Can you fix it yourself?
Yes — replace the element and reset the maintenance counter. This is routine operator-level maintenance, no service call needed.
Step by step — what to try, in order:
- Replace the air filter element.
- Reset the maintenance counter on the controller.
When do you need a technician — and why?
Only a warning that will not clear after a genuine replacement and counter reset needs service attention on the controller side.
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 0028 W — Air filter h ⇞ mean on a Kaeser Sigma Control 2?
Air filter maintenance interval expired. The service-hour interval for the air filter has expired; replace the air filter.
Can I fix 0028 W — Air filter h ⇞ on a Kaeser Sigma Control 2 myself?
Yes — replace the element and reset the maintenance counter. This is routine operator-level maintenance, no service call needed.
When does 0028 W — Air filter h ⇞ on a Kaeser Sigma Control 2 need a technician?
Only a warning that will not clear after a genuine replacement and counter reset needs service attention on the controller side. Routine DIY maintenance; no service call needed unless the warning will not clear.
Verified against service documentation: Kaeser Sigma Control 2 documentation for 0028 W — Air filter h ⇞ (airsolcan.com)