My P1S started giving this fault code after installing the Biqu LED consistently at the beginning of the print when Bed Leveling is enabled. If I disabled Bed Leveling, no issues. When I get home today I plan to disconnect the Biqu LED and plug in the OEM LED light and run it for a while to see if the issue continues. If it does, I’ll begin diving into the tool head fixes others have suggested.
I’ve been struggling with this now for about 7 months
I have a P1P that was upgraded to a P1S with the official kit.
Randomly it started throwing the toolhead front cover error - but every time I go and check it’s all on fine.
If I get hold of the cover and take it on and off a bunch of times it seems to clear and I can print.
Sometimes it will go weeks and weeks without issues, then all of a sudden it will start doing it again on every print
It’s very frustrating and there doesn’t seem to be any clear path to solving it 
Did you read through this thread? The solutions is right there. Have you tried this?
https://forum.bambulab.com/t/toolhead-front-cover-has-fallen-off/112799/2#p-301100-possible-remedy-2
This remedy has been working now since last summer without incident.
I haven’t tried that no
I did all the steps on the bambu wiki - took the casings off, front middle and back, then checked all the wiring was secure
Disconnected and reconnected a few times, checked it was clean - no difference as soon as I start a print it throws the error
I’ll try taking the screws out the middle housing and see if it fixes it - but if it does I’ll be contacting customer service because just leaving the casing loose isn’t a proper solution IMO. There must be a design flaw that needs fixing
One other thing to check is if you have anything plugged into the USB connector on the back for the control board. If you do, try removing it and seeing if this solves the issue. I had this exact problem and that’s what solved it.
Welcome to the way… “Chabuduo” (差不多)
We in the west may consider this a design flaw and I would 100% agree with you. However, in China, this is “Close enough” or Chabuduo
Whether this is a design defect or not, the solution is a workaround so one must decide whether this is the hill to die on and take Bambu Lab to task. But if your phone doesn’t ring… that’s their tech support at the other end.
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You might also want to make sure the screw that sets the extruder’s tension against the filament is screwed in all the way.
The screw head can cause the middle cover to bulge out on the right side and even an almost invisible amount of bulge can cause the “Cover has fallen off”" fault.
Thanks, I have nothing in the USB connector, no extra lights or anything - it’s an “as it comes” P1S basically
I’ll check the extruder tension screw to make sure it hasn’t worked loose
Hello!
I have the same problem since yesterday. HMS_0300-1200-0002-0001: The front cover of the toolhead fell off. The USB is equipped with Panda Touch with their new temperature sensor. The lighting is also included. What is my suggestion? . Simple, cheap and fast. Three magnets. 8x2. I can’t attach pictures? Why? Put the magnets behind the one used for the sensor. On the inside.
Just so you realize, the root problem is probably the Panda hardware which has been amply documented in the forum.
Just be aware that clearing the fault via the magnets may put the Bambu board with the USB-A port at risk of damage.
I had the same type of false front cover error myself, and like you guys thought it was something to do with the hall effect sensor. So i ordered a new board with the hall sensor in question on it. In the meantime, i notified bambu lab of the error woes i was having, and their tech team asked me to try inputting an extra line into the start up gcode of my printer. I did as they asked and my printer seems to be operating well again and has for a couple of weeks now.
See above screenshot with the g code command in the red box at the position it is to be added. Hope this helps someone out there.
Did they explain what this G-code is supposed to do?
I wonder if it just tells the device to ignore the sensor error.
No they didn’t and probably wouldn’t. I think you may be spot on though, and it’s my guess also that it just tells it to ignore the sensor error in question.
If anyone does know exactly what that gcode command does i would like to know. I am far from expert in these matters.
G code :- “M630 S0 P0”
Does it issue a new value for the hall sensor to accept?
My exact question being What does that G-Code line do.?
There is a 2024 vintage forum post, Front Cover of Tool Holder Fell Off Message but I also had this same issue later than June 2024 and they ended up swapping out my printer for a new one.
Seems like that cover fault continues to bite Bambu Lab. The length of time this fault has continued with no permanent fix makes it seem like the g-code string is not a fix as much as a quick and dirty band-aid that is an ongoing problem.
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Yes it definately feels like a quick ‘n’ dirty fix. knowing exactly what that gcode does would reveal whatever the problem is.
Front Cover Malfunction
01S00C330700201
25/04/18 13:52
In Progress
Today is 25/0427 and no answer from Bamboo. 
Try removing ALL of the Panda electronics that is being powered from the USB-A port. Your stack of magnets did not fix??
That port won’t support the electrical demand of the Panda hardware
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Guys, All I know is that I had this problem and found the G-Code modfication posting that bypasses the front end attached check. Once I applied this G-Code change I have never seen this problem again.