Bambu Lab AMS shows offline: causes and fixes

An AMS (Automatic Material System) that shows offline has lost its link to the printer over the Bambu Bus cable, which carries its power and data. Turn the printer off and reseat the 4-pin and 6-pin cables at every joint: the printer, the filament buffer or AMS Hub, and the AMS. Then power on and update the firmware.

This is a hardware fault, not a network one: the AMS talks to the printer only through that cable, never over Wi-Fi or Bambu Cloud. If Bambu Handy or Bambu Studio shows the whole printer offline, see Bambu Lab printer shows offline instead. Codes, menu names and values below follow Bambu Lab’s wiki and Bambu Studio as of November 7, 2026.

Why does my Bambu Lab AMS say offline?

Your Bambu Lab AMS says offline because the printer has lost its signal over the Bambu Bus cable. Bambu Lab lists three causes: a loose connector, a broken cable, or a failed AMS circuit board. Mismatched AMS firmware, the older 6-pin cable on a newer AMS, and a wrong AMS Type setting on an A1 also break the link.

The AMS lights and the printer’s HMS (Health Management System) error codes narrow it down:

In an HMS code, the first group names the unit. 0700 to 0703 are AMS A to D (an AMS or AMS 2 Pro), 1800 to 1807 are AMS HT A to H, and 1200 to 1203 are AMS lite A to D. So 1800-5000-0002-0001 is the communication fault on the first AMS HT. Connected one at a time, the unit wired to the printer, buffer or hub becomes A and the next in the chain B. The letter tells you which cable to check first.

How do you fix a Bambu Lab AMS that shows offline?

Turn the printer off. Unplug and reseat every Bambu Bus cable from the printer to the AMS, including the filament buffer or AMS Hub, and check the pins for damage. Power on. If the AMS comes back, update the printer and AMS firmware. If it does not, replace the cable or measure it with a multimeter.

How to fix an offline Bambu Lab AMS, step by step

1. Turn the printer off. Bambu Lab’s procedure starts with the printer off. The AMS draws its 24 V supply from the printer through the same bus cable.
2. Trace the cable chain. Every plug is a place to fail:
   • X1 and P1 series: a 4-pin cable from the printer to the bottom of the filament buffer on the back of the printer, then a 6-pin cable from the left side of the buffer to the AMS. With two or more units, an AMS Hub replaces the buffer and each extra AMS plugs into the second 6-pin port of the previous unit.
   • A1 and A1 mini with an AMS lite: one 4-pin cable from the printer to the AMS lite, with no buffer.
   • A1 and A1 mini with an AMS, AMS 2 Pro or AMS HT: a 4-pin cable from the printer to the A1 Series AMS Hub, then a 6-pin cable to the AMS.
   • H2 series: a 6-pin cable from the printer straight to either 6-pin port on the AMS; the buffer is built into the printer.
   • P2S: a 6-pin cable from the AMS to the printer’s filament buffer. Only one of the buffer’s two 6-pin ports takes AMS units; the other is a spare.
   • Unit limits: four AMS units of any type on the X1, P1 and A1 series (or one AMS lite on an A1). The P2S takes four AMS 2 Pro plus four AMS HT; the H2 series and X2D take four AMS 2 Pro plus eight AMS HT.
3. Reseat every plug and inspect the pins. Unplug both ends of each cable and push them back in until they lock. Bambu says a seated plug should not come out by hand without pressing its locking tab. Look for splayed or bent pins and for water corrosion on the AMS board’s connector. Replace any cable with damaged pins. Insert the 4-pin cable the right way round, following the text printed on an L-shaped plug: Bambu warns that a reversed one can burn out the printer and AMS mainboards.
4. Wiggle-test the plugs. With the printer on, flex each plug and cable, or ease a plug partway out of its socket. If the AMS appears for a moment, Bambu says the fault is in that plug or cable. If nothing changes, Bambu’s next check is the bus and power cable inside the AMS, reached by lifting out its main frame.
5. Use the right 6-pin cable. The AMS 2 Pro and AMS HT ship with a newer 6-pin cable with a 2.5 mm step height; the original AMS cable’s step is 1.1 mm. Bambu says the older cable on an AMS 2 Pro or AMS HT “may cause unstable communication”, while the newer cable also works on the original AMS. Swapping in a spare is the quickest way to test the cable.
6. Update the printer and AMS firmware. Once the AMS shows on the screen, install any pending update. Bambu says the printer, AMS Hub and AMS firmware must match or printing may fail, and the mismatch codes ask you to upgrade on the “Firmware” page. If the update fails, unplug the AMS and update the printer alone. Then reconnect the AMS and update again. If the printer updates but the AMS does not, Bambu points to the AMS connection or the AMS mainboard. A stalled update is covered in Bambu Lab firmware update stuck.
7. On an A1 or A1 mini, check the AMS Type. Under Settings > AMS Options > AMS Type, the printer must be set to the kind of AMS you have connected. Bambu says connecting an AMS before switching the type “may cause communication loss and errors”: unplug the old unit, switch the type, then plug in the new unit.
8. Measure the cables with a multimeter. With the printer off, measure the resistance across the pins of the printer’s port, each cable end and the AMS port. Compare the readings with Bambu Lab’s values below; any part that reads out of range is faulty.
9. Open a ticket with Bambu Lab. If every reading is normal and the AMS is still offline, Bambu asks for a support ticket with your resistance readings, recent printer logs and photos or video of the fault. If the readings point to a failed board, check Bambu Lab’s warranty terms before buying a replacement.

Measure the cables with a multimeter

Bambu Lab publishes the normal readings, taken with the printer off. For the AMS port, unplug its 6-pin cable at the far end (the buffer, hub or printer) but leave it on the AMS. Let the AMS sit unpowered for at least a minute first. GND is the ground pin; sigA and sigB are the two signal pins, marked in Bambu’s diagrams.

An out-of-range AMS reading points to the AMS mainboard, or to its power board if the mainboard’s own connectors read normally. An out-of-range printer port points to the printer’s AMS interface board, behind its back cover, or its MC board. Bambu’s full procedure covers all eight measuring points.

For an AMS lite, unplug its 4-pin cable from the printer, wait a minute and measure across the plug. Bambu’s normal values for the six points in its diagram, R1 to R6, are 320 Ω, 130 kΩ, 2.7 kΩ, 130 kΩ, 2.7 kΩ and 130 kΩ. R4 shorted or under 500 Ω means a faulty AMS lite mainboard, and so does point C or D reading open to the others. On the A1 and A1 mini, the printer’s own 4-pin port should read about 4.5 to 5 kΩ between pins A and C and between A and D, with the printer off.

24 V check. If no slot lights up at all, measure voltage instead. With the printer on, the 4-pin cable unplugged from the buffer should read 24 V, and so should the 6-pin cable unplugged from the AMS.

For an AMS lite, measure about 24 V at the printer’s 4-pin port. If an A1 shows no 24 V there, Bambu points to a loose cable between the mainboard and the interface board under the bottom cover, a check it does not list for the A1 mini.

AMS offline on a Bambu Lab P1S, X1C, A1 or H2D

Bambu Lab P1S AMS is offline

On a Bambu Lab P1S or P1P, the chain is the 4-pin cable from the printer to the filament buffer on its back, then the 6-pin cable to the AMS.

• AMS 2 Pro and AMS HT need P1 firmware 01.08.00.00 or later. Bambu says to update the printer before connecting them. For a microSD update from older firmware, unplug the AMS 2 Pro or AMS HT and update. Then reconnect it and update again.
• Older firmware goes through a bridge version. A P1 below 01.09.01.00 must first take 01.09.01.00 by offline upgrade before any later version. That release (January 14, 2026) also “Fixed an occasional AMS communication issue.”
• Recommended AMS versions. With P1 firmware 01.10.00.00 (March 30, 2026), Bambu recommends AMS firmware 01.00.06.83 and AMS 2 Pro and AMS HT firmware 03.00.21.29. The printer’s system settings show each AMS’s installed version and serial number.

Bambu Lab X1C or X1E AMS is offline

The X1C uses the same 4-pin and 6-pin chain as the P1S. AMS 2 Pro and AMS HT support arrived in X1 firmware 01.09.00.00 (April 29, 2025), and Bambu warns that with one of them connected “the firmware update might not be initialized, or could fail.” For a microSD update from older firmware, Bambu says to install 01.08.50.32 with them unplugged. Then reconnect them and update to the latest version. The X1E’s printer port reads about half the X1C’s values in the table.

Bambu Lab A1 AMS lite is offline

The AMS lite plugs straight into the A1 or A1 mini with one 4-pin cable. Bambu separates two faults. An AMS lite that fails to power on has all four slot lights dark; one that has lost communication blinks red in all four slots.

• Set the AMS Type before connecting a unit (step 7). Since firmware 01.07.00.00 (October 27, 2025), the A1 series also takes an AMS, AMS 2 Pro or AMS HT through the A1 Series AMS Hub. It never mixes them with an AMS lite. The X1 and P1 buffer or AMS Hub must not be used on an A1: Bambu says they “may lead to communication abnormalities or buffer damage.” Setup is in upgrading an A1 mini with an AMS lite.
• Update the firmware. Version 01.04.00.00 for the A1 and A1 mini “Fixed a low chance issue of the AMS lite not being recognized by the printer.”
• Prefer online updates. Bambu’s A1 notes say an offline update fails on firmware 01.06.00.00 or earlier while an AMS, AMS 2 Pro or AMS HT is connected.

Bambu Lab H2D AMS 2 Pro or AMS HT is offline

The H2D uses no 4-pin cable: a 6-pin cable runs from the printer to either 6-pin port on the AMS, and the buffer is built in. More units chain from the second 6-pin port, and the unit wired to the printer is AMS A.

• Use the matching 6-pin cable. Use the one that came with the AMS 2 Pro or AMS HT, not one from an original AMS.
• Run AMS Setup after connecting. The first time you connect an AMS 2 Pro, Bambu says to run AMS Setup (Filament > AMS Setup, Auto Mode or Manual Mode) so the H2D finds which extruder it feeds. HMS 0700-5500-0001-0003, or 1800-5500-0001-0003 for an AMS HT, means the unit dropped out during that process.
• Drying power is separate from the link. The H2D can power one AMS 2 Pro for drying; more need the 24 V, 4 A Switching Adapter, and an AMS HT always needs its own power cable to dry. A power-limit message about drying does not mean the AMS is offline.
• Keep the firmware current. H2D firmware 01.01.01.00 (April 10, 2025) “Optimized AMS hardware recognition mechanism, which fixed the print job cancellation issue caused by AMS recognition errors.”