Buderus GB142 fault 6 A, gurgling sounds

[000utback]

Buderus GB142/30 about 4 yrs old running hot water radiators, sections of floor warming, and indirect domestic hot water. Over the summer, I noticed the floor was wet from the pressure relief valve, although it never vented while I was in the room. I put a can under it to contain the water but didn't check it regularly. Now the boiler is shutting off with a 6 A code. (manual says "no ionization message after ignition") Also, there's a lot of gurgling noise, like a lot of air bubbles or maybe it's low on water. Had a serviceman out in the summer and he couldn't figure out why it was venting. Had a serviceman today and he can't figure out the error code. He did a reset and it ran for awhile. after that every time we did a reset, it ran for a shorter period of time. Called afterhours service, and their only guy who knows this stuff is out of town till Wednesday.
Any quick suggestions? We can handle the heat with the woodstove and space heaters, but really missing the hot water showers. I figure tomorrow first thing I'll bleed the radiators and see if it takes in make-up water.

 

[Fitter30]

Burner controls aren't seeing the flame either by not lighting or failed part. Look at page 65

https://www.google.com/url?q=https://www.powerequipmentdirect.com/manuals/GB142Service.pdf&sa=U&ved=2ahUKEwjsjae6nL_6AhWeLkQIHbZBBM8QFnoECAUQAg&usg=AOvVaw04_PpssU-i9ahugvavdTeV

Has the boiler been serviced every year and cleaned dhw water side? Gurgling on which side of boiler or dhw?

 

[Sponsor]

 

[000utback]

Thanks for sending the manual and the page highlight. This is propane-fired, so I'll follow through that path.
I disabled the pumps to confirm that the gurgling happens when the blower runs. So...that means there's water on the flame side. Either an issue with condensate or a leak?
The unit was shut off all night, and started up fine this morning. Ran hard to get the DHW hot, then serviced house heating. But after awhile it was gurgling again, and eventually faulted out. There was vapor coming out of the exhaust pipe.
I've been letting it cool down again. Interested in opening it up and seeing where the water is. I'll follow the electrical troubleshooting from your manual as well.

 

[000utback]

Emergency over. The condensate drain was almost totally plugged. That's why it ran okay after sitting for 12 hrs, but then starts to bubble again. This thing is filthy, and the last guy pinched the gasket when he put the bottom plate on. Hope I can get it to seal. I think that my expensive annual cleaning was not being done right.