Best solution is to dry the PETG filament in a dryer. (New) Silicagel in the AMS prevents the filament getting wet. It wil not dry the filament.
Dry filament and clean build plate is the first thing to start with.
But the filament is brand new (unsealed just before inserting in the AMS)
And if i need to dry it, can i use the Bambulab dry function?
I have printed PETG for 5 years already (different brand) with a Prusa without filament dryer. I never had this before
Build plate is completely cleaned with soap. Do i need to use 99.9% alcohol? (Both on textured plate and Engineering plate?)
Even new filament can be wet.
I never used the BL dry function. I have got S1 and S2 Sunlu dryers.
Do not count on new filament being dry. It is good practice to always dry even new filament. If it is wet in the bag, chances are high that the desiccant in the bag is also wet.
And of course you’ll need to clean the LIDAR lenses before filament calibration. I have noticed PETG to cause a lot of dust compared to PLA, so cleaning becomes much more frequent.
Can i place multiple rolls of filament in the printer to dry? It takes 12 hours and if i can only place 1 at a time the first will be wet again before the last is dry.
I cleaned the camera with alcohol and the lens was dirty but is clear now.
I did the calibration but it creates a new profile. After inserting a bambulab spool it takes it’s own profile right? Or do i need another type of calibration?
To be honest, I am too impatient with the maximum drying times given by Bambu 
I usually just bake the rolls between 2-4 hours per side. One in my dryer, one in the printer. Been lucky so far. I have not yet printed CF filaments with the Bambu though.
There are a few threads here on calibration, in particular using Orca. For me, the filament calibrations in Studio are still OK.
Thank you, i just put 1 roll in a cardboard box and started the drying process. I feel a bit anxious to put a cardboard box for 12 hours in a printer with a 90 degree celcius bed.
I will try with that one roll tomorrow. If that helps i will try to put 4 rolls in the printer to dry simultaneously another time
You need more than double that temp to ignite cardboard. Lots of us dry filament this way.
Okay, and how about putting 4 rolls inside (or 2 or 3 if 4 don’t fit). Will that work as well?
Famously, paper needs Fahrenheit 451 (~232°C) to ignite. 
Additional rolls will benefit from the heat and at least the lowest half of the lowest roll should not see so much of a difference. But you do not really know about the humidity in the upper rolls and you loose the benefit of the heat trapping lid.
Still, my dryer only does a maximum of 5h with a wide temp range from bottom to top and has no chance of reaching 90° at all anywhere. So I guess using 12h at 90°C should easily be good for 2-3 rolls. Especially if you turn and swap them around every couple of hours. Only a guess though.
In the long run, it is easiest to get a dryer. We want to make and print, not watch filament dry
Always dry filaments before use. Even sealed in Vacuum they may be wet.
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After drying the filament for 12 hours i printed another part. I still have some strange effects. The AMS now shows green on the humidity meter as well
So with the filament being dry (and the LIDAR cleaned and the filament calibrated) you can look at the settings.
While not having printed PETG-CF yet, I have resolved similar surface issues by printing slowly with different fan speeds and additional top surface layers to effectively cover over these types of top surface defects.
However, there are now better solutions here in the forum. Try settings from here or, more for the CF loaded PETG, here.
How do i need to calibrate the filament, does it make a new profile? I don’t completely understand what is best to do because the printer detects it by itself.
The lidar is clean but i still get the error message.
The material i use is PETG basic, not CF. And it printed fine before. It started doing this slowly in the last 1.5 / 2 weeks i think
A mistake is always an unfortunate sequence. With Bambulab you can go fast, a little sand in the Formula One car and you drag it all over the race track. So you have to get one parameter better - then the final total will be balanced.
May and since it`s PETG:
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Do a first layer print at 50mm/s - Then you rule out a lot and already show in which direction you have to move.
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Cleaned the black texture plates very thoroughly (Isopropanol).
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Pay attention to which side of which textured plate you used. May all sides are aleady gone. Maybe it’s just one small zone how is gone and once there’s dirt on the nozzle, then the adhesion in the good zones is also gone. And this is no longer compensated for over the next layers, you just move on from layer to layer. Not like the old slow printers, where the error was simply overprinted by the next layer…
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I printed the first layer a little deeper so that it pressed more into the plate…
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Cleaned all dirt after every print, even under the silicone sock. A lot of dirt can build up there and then a lot builds up very quickly.
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Z-hopping + layer height below 0.45 can become very critical at high traversing speeds (moving to the new printing position without printing). The Nosel can not melts the strings in the Z axis fast enough out of the way when driving over, this can lead to a lot of microcollisions, which in total can lead to the tearing off of the first layer - and that only has to happen once and then the dirt is back on the nozzle and the adhesion of the first layer is gone.
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But the last thing on my mind is wet filament. I should see it blow bubbels but i can`t. In your case I see pathrise and no liability of the first layer.
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Incorrect route energy (sum of heat quantity, time and travel speed)
But even I can be wrong sometimes… I have black texture plates in the trash, I only have the gold ones, 5% Less of these problems
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Regarding wet filament:
I ordered some other brand, brand new bag, printed and had all kind of print issues (layers separating, filament clogging nozzle, uneven layers, even tested extruding filament and saw bubbles appearing). Sometimes it was ok, but mostly had failures.
I really had no clue what was going on untill I tried to dry filament.
I used my microwave oven (but in convenction mode) and set it to 50C. Used old kitchen rag and wrap PLA spool in that. Considering I can only set to 1hour timer, i did that for at least 5-6 times. No more print quality issues.
So you can try this method to dehumidfy your filament and i would advise to use rag like i did, so that the spool is not directly exposed on oven heater. And yea, different fillaments require different temperatures (PLA is safe with 50C, PETG needs higher I think, ABS also higher…) so take that into considering.
The 1st time I cleaned my LIDAR, I kept getting that message too. Turned out I had not seen the diodes as it is tricky to get a good view there. Check the wiki for that. Once cleaned with IPA and a Q-tip, it went away with the next self-test.
Calibration in Bambu Studio is straightforward. Just go to the Calibration and run through the steps. Just don’t confirm a succesful calibration print in the printer before saving it through BS.
Further options are in Orca slicer but BS aleready covers a lot of ground.
I had a similar problem and it was not wet filament. PETG is extremely sticky, and it sticks to, and builds up on, the nozzle. When enough of it builds up, a lump can fall off and end up on your print and get dragged around. So first thing, I’d watch your nozzle closely while printing and see if that’s what happening.
When I noticed this, I started doing some test prints. A temperature tower indicated that the print head temperature should be higher than I was using. When I print PETG around 275-280C, it works great! Yes, I know that’s higher than the recommended temperature range for PETG, but it seemed to work well for me. At a higher temperature, the PETG is more fluid and doesn’t stick to the nozzle nearly as much. I also needed to turn the part cooling way down, and turn up the chamber cooling.
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I find printing my Orange EYRONE PETG at these high temperatures also works really well!
Thanks for all the replies. I cleaned my lidar sensor better and i didn’t get the warning anymore. I also printed the hygrometer bins and inserted silica-gel. So far the prints are good again
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