I have found out that the HUB motor will not allow the filament to enter the extruder from any of the ports.
I removed the power cable and then re-inserted it and the system came alive.
I was able to print one more project.
Has someone come across this before?
I’m having the same problem.
Had all 4 feeders fail within 3 weeks of each other. got them replaced and bought a new main board to go with them just incase. The old board was faulty too so it was a good decision. However on the new board i get all 4 feeders flash the double red lights. Device tab in Bambu studio shows No AMS.
All cables are connected tightly
Maybe try replacing cables?
I bought the cable replacement kit that was supposed to contain a 485 ( comms cable ) but it didn’t have one
Contact Bambu, when aren’t backed up with 1000’s of orders their customer service is actually quite great. Also what about external cables, is it possible one of them has been damaged? If the problem cannot be fixed Bambu may send you a new AMS.
Sadly enough it started again. Checked all connections. No luck. Every time it happens with pulling back filament. The device shows that suddenly the exeternal spool is used and filament could’nt be pulled back. But the external spool is not used. It was pulling back ASA filament from a print that was just done. I tried to load filament to the tube, let it purge and see that it was done. Then follow the messages on the display to pull out the filament again. But it didnt resolve the issue. On the devise tab it still shows that the exteral filament spool is used and there are no spools in the AMS show on the display. Teddy, are you able to assist? 
Just now I disconnected the AMS and let the X1C perform a device self-test. When the test was done I connected the AMS again, the spools where recorgnised (it read all the NFC’s of the spools again) and the error was resolved. Dont’s know how and why this happens. For now it seems resolved. Lets hope it stayes that way.
The same problem occurred with my two AMS units, all flashing red. Using the diagnostic instructions provided by Bambu Labs, I tested sig-A and Sig-B’s resistance to each other and to ground, then sent the results to Bambu Labs. I had to replace the motherboard and communication board on each AMS. My hub tested ok. After replacing the components everything worked as expected.
Just had the same problem with the red blinking lights on the AMS. Funny thing is that they will do this sometimes in the middle of a print and still print. I changed the Bus cable, the power board…and it was fine and then in the middle of a print again, all the lights started blinking. I may try to replace the cables next.
No way. This actually fixed it for me. thanks for posting this!
I have been messing with this issue for a couple months and although I feel like an idiot after finding the solution I thought Id hop on here in case someone is dealing with the same. After orderinga new 6 pin communicatio cable for my AMS I have no realized that the cable is single direction. Meaning one end of the Cable has a label “C” which must be connected to the AMS for proper communication, if you have it backwards you will get the four flashing red LEDS. SO there you go. try reversing taht cable before you tear your printer apart.
I just updated my firmware on my Bambu Carbon X-1 and now the AMS is all blinking red… thus how I found your post. I’m not sure where to begin as I am a newbie. I’ve turned everything off and on and it will not let me remove 2 of the filaments. I will be trying to go through each thing but I am not comfortable taking my machine apart. Ugh.
I just went through a bout with red blinking lights again. It was the connectors on the back of the printer. One for the hub and the other one connecting to the AMS. Reseated the connectors, the AMS did fine for a week before it did it again.
I bought this stuff.
A little dab will do ya. Its been fine now for three weeks. 
Time will tell.
Update: I just plugged the back into the other AMS slot and everthing went back to normal. I eventually reset everything and moved back to the first slot and working fine. Thanks for the help.
I’ve had this issue, intermittently, for the last few months. I noticed if I print anything that’s not PLA, I get the red blinking lights on all 4 AMS units. My thought is, my 110v 15amp circuit may be pushed too far for my 2 X1Cs and all their AMS units (6 in total) to print higher temp materials, at least at the same time. I have my H2D and 2 AMS and HTs on a dedicated 20amp circuit, and no issues thus far.
I asked ChatGPT for the info below, so grain of salt, but I’m sure it’s not far off. If I kick off 2 prints simultaneously, with say ABS for both, my theoretical max amperage draw could be around 9.5amps each for bed heating during startup.
I’ve never tripped the breaker, so this conjecture might be misguided.
Total Amperage at 110V (US standard voltage)
Total Estimated Amperage
| Scenario | Total Amps (approx) |
|---|---|
| Typical Load | 2.3 A + 0.18 A ≈ 2.5 A |
| Peak Load | 9.1 A + 0.36 A ≈ 9.5 A |