Ive just got my p1s deliverd, and i connected the AMS, it worked, then i moved my printer to my bedroom and since then the AMS is not working. The printers says the AMS is ofline and the four lights are blinking red. i tried everything with the cables. but nothing worked. now i am really bumped about it because i wanted to print realy bad. 
i checked the motherboard of the AMS if the cables were good they are all the way in. I checked the tubes if there was any left over White Fillament there isn’t. it seems the 4 pin cable from the buffer to the printer. on the printer side it looks like it is loose, but still nothing happens when i push the cable in and i hold the cable. can somebody help me please? i dont know what to do, i already put a support ticket out.
It normally means the cables are not quite connected.
Try:
- Power everything off
- Remove the black data cables
- Wait a few minutes
- Plug the cables back in
- The one from the printer to the buffer or hub
- The one from the buffer or hub to the AMS
If you have more than one AMS - From the first AMS to the second
- Repeat until all AMS are connected
- Switch the printer back on
Ive tried this mutiple times but still no connection
Are you able to show some photos of how the AMS is connected to the P1S?
Just wanted to confirm that it looked something like this:
This diagram and wiki helped a lot since I am a more visual troubleshooter.
Hi DitIsChristian,
I purchased a P1S Combo in late June of 2025 and also encountered AMS v1 issues.
My AMS seemed to work for a few hours but soon started flashing red LEDs afterwards.
I will go through the troubleshooting I did, the parts that were replaced (needlessly), and what was finally diagnosed as the solution.
This occurred over the course of two months.
I initially just avoided using the AMS as I didn’t need it.
My wife however, really wanted to take advantage of the multi-color option.
And I had previously hoped to use the feature where you can continue using a second spool of similar color that is of the same filament type.
In the diagnosis of my particular AMS v1, the 4-pin and 6-pin cables were replaced multiple times.
Please note that if you can use a simple multi-meter to check continuity on the external 6-pin cable of the AMS, you can quickly verify if there’s continuity from one end of the cable to the next.
Checking the 4-pin cable is similar, except one of the connections is reversed or slightly different.
The Bambulabs troubleshooting wiki explains this much better than I can.
I did not pick up on that 4-pin subtlety the first time, diagnosing the 4-pin cable as faulty when it was actually just fine.
I also replaced the buffer device behind the P1S twice.
The resistance measurements given on the Bambulabs wiki showed my connections to the buffer as all open circuits instead of the given resistance values on the troubleshooting wiki.
The tiny power board behind the AMS where you plug in the 6-pin cable was replaced.
The main board inside the AMS board was also replaced.
Replacing all these parts DID NOT SOLVE MY ISSUE.
From the very first time I opened the AMS unit, I watched numerous videos online and was reminded to be extra careful about the 5-pin cable INSIDE THE AMS connecting the main circuit board to the back power panel.
=====> It’s a CRAPPY FLIMSY connector that barely gives you any feedback about whether you’ve connected it properly once you re-insert it. <=====
I suspected from the very first day I opened the AMS that that very flimsy 5-pin data cable which barely had any slack when you opened the AMS, could cause me problems.
It was a gut feeling.
Fast forward two months later, when my Bambulabs reseller invites me to bring my AMS unit into his store to try a few additional troubleshooting steps.
One of these was substituting a KNOWN GOOD 5-pin ribbon CABLE from another fully functioning AMS v1 unit and within seconds the AMS was fully functional.
If you follow the signal path from the P1S to the AMS, it begins at a small circuit board inside the P1S, then continues outside to a 4-pin cable travelling to the buffer unit.
Then, the digital signals leave the buffer unit and go to the AMS where they eventually arrive into the main board (via that crappy 5-pin internal ribbon data cable).
The ONLY part I had not swapped/changed was that internal circuit board inside the P1S Printer which, every time I measured the resistance values as shown by Bambulabs wiki, was within the acceptable tolerance values.
Those thin ribbon cables and connectors inside the AMS are one of the easiest points of failure.
EVERY TIME you open the AMS, even if you’re incredibly careful, that 5-pin data cable could quickly become too loose to make a decent connection.
It only takes one bad pin connection to fail and the software inside the P1S will report that it can’t talk to the AMS.
The only moving parts in the AMS is that one motor.
The RFID circuit boards inside that AMS don’t move.
There’s practically no moving parts.
It shouldn’t fail.
Same with the buffer behind the AMS.
There’s a spring activated sensor, and everything else is just static parts.
By the way, that crappy 5-pin ribbon connector inside the AMS I measured for connectivity multiple times and there was always full connectivity between both ends of each wire in the 5-pin ribbon.
AND YET…
when you inserted that 5-pin connector to the rear port of the AMS, it felt like it was barely holding on.
This should be redesigned with a beefier connector where you can “feel” the snap as you push it in.
So, that’s how my AMS was finally brought back to life.
That was in early September.
It’s still running perfectly since then.
I’m actually scared of opening up the AMS now until I have a spare 5-pin main board to the power board spare cable.
If you are not comfortable using a multi-meter to test for resistance values given on Bambulabs troubleshooting wiki, perhaps you know a technical minded friend who could help.
ALWAYS perform these multi-meter resistance tests with the POWER PLUG pulled out.
There is always the possibility that a bad integrated circuit failed on one of the circuit boards.
I was able to measure the correct voltage from the 4-pin connector behind the P1S printer 4-port connector all the way to the AMS Main Board inside.
So the AMS was getting power.
But it was not sending either any digital signals or some of the required acknowledgment signals to the P1S.
All because of a crappy 5-pin ribbon cable between the AMS Main Board and the rear power port of the AMS.
Which Tech Support should be able to send you free of charge.
Or, if you bought it from a Bambulabs reseller who stocks parts, and they are located nearby, you can quickly obtain spare parts free, authorized by Bambulabs Tech Support after you submit your issue.
Be detailed, and clear about what troubleshooting steps you have tried.
I submitted as per their wiki, full measurements as they demonstrated in their data measurement chart.
Their wiki is very very useful.
Well written.
Great pictures.
Their wiki crew is to be commended for their work.
Be aware that I rarely check in on these forums very often so cannot answer additional questions.
Good Luck on your quest.
Hopefully you can get it fully functional quickly.
tldr: He had the same problem as the OP, the 5 pin cable was bad, it’s working now.
This worked for me. Thank you for the post.