by Mark
(Baltimore Maryland)

Critical error code 300A on Kaeser compressor.

What is this error code and what does it mean?


Critical Error 300A
by: Carls421

The Critical Error on the Kaesars Sigma controller means there is a software error on the actual controller, the compressor itself is all fine but your controller is no longer usable which means it needs replacing.

Kaeser compressor Sigma controller

Kaeser compressor Sigma controller

Sometimes you can turn the machine off at the main isolator for 5 minutes then switch back on again and it will work for anything between 5 minutes to a few weeks, but it will come back, so unfortunately it does need replacing.

Be warned, these are very expensive depending on which one you have (Sigma Basic is the cheapest, Sigma 1 most expensive) you’re looking at between £800-£2000 for replacement.

But check with your local HPC supplier. I’m in East Anglia in England. Where abouts are you?

Sorry for the bad news but hope that helps



is replacing the Sigma control the only fix?
by: Ron

Thanks for the information Carl. I’m in Southern California. There is nothing else that can be done to fix the sigma control besides replacing it?
Thanks again,


by: Carls421

Hi Ron,
Your only last hope is getting it whats called “K-loaded” by the manufacturer, this means the software totally wiped and put on again. I don’t know how much that costs but the critical error can still reappear at some point so it a bit of a gamble. Id get in touch with your nearest HPC distributor to see what they will do for you, obviously they may just say buy a new one but ask about getting it K-loaded first. That really is your last option unfortunately.
Having a critical error is really quite rare like i said but it can happen very randomly. One of the 3 i have seen in the 20 years of working on air compressors, happened whilst i was servicing it. Trying to explain to the customer that it wasn’t anything i had done was a nightmare! You are one of the unlucky ones im afraid to say. 🙁
Carl, just another thank you from me for for once again taking the time to respond to Ron on this post. Your comments and advice are read by many, not just the one to whom you respond. Your information is valued and appreciated.


Sigma Control
by: Anonymous

Just make sure when you get a new control module that it is actually set up to work when it is installed. I Bought a new one from an authorized Kaeser distributor under the understanding that it was set up and ready to go. We installed it but not only was the display in German (which I changed) But it needs a level 5 password to get it up and running. Not much chance of that as they want to send their service tech out and charge me about Eight hours travel time plus the service fee. In retrospect I should have scrapped the compressor and replaced it with something more user friendly.


Error message sigma controllers
by: Anonymous

the sigma controllers are notorious for the error message. we have seen probably about 10 controllers with the same error , it is a small relay on the controller that creates the message unfortunately kaeser in there wisdom do not have error on there machines so we are told.. LOL

Sigma Controller

by: Carl

Hi again
Just to clarify, it is ONLY the Sigma 1 NOT the Sigma Basic or the Signa 2 that have the Critical Error issue.

The Sigma 1 controller is no longer made so you will be lucky to actually get a new one from the manufacturer.

Yes, you do need the level 5 code to set it up but if you have ordered one and have had it delivered from a registered HPC/Kaeser distributor then you should have given the compressors details and it should have already been set up before delivery.

If it hasn’t been set up properly then HPC should have asked you to either send it back or they should send an engineer out free of charge to set it up. They wouldn’t/shouldn’t send a raw controller out that hasn’t been set up properly if they were a proper distributor


by: Anonymous

I had the same situation myself where a Kaeser distributor sold me a controller that was not set up for the particular machine even though I had given the correct model, serial number and part number.

It was an eight hour round trip for this job so to say I was annoyed would be mildly put, especially when they said that they would need to send out the Kaeser technician to set it up and charge me for a whole days labour and travel for an item that I was assured was plug and play.

The other alternative was to return it but hey said I would be charged a programming fee.

Needless to say I did not go down that path and did some searching around until I eventually discovered the level 5 code and set it up myself.

It has now been working fine for a couple of years.

Level 5 pass
by: Anonymous

Anyone have the Pass desperate for it?


Kaeser controller code level 7.
by: Anonymous

11TTY or 3WW50 is level 7 in Australia it mite work where you are.