The Prusa XL runs the same QR-linked error architecture as the MK4, MK4S, CORE One, and MINI+: a five-digit code in the pattern XXYZZ, where XX identifies the printer (17 for the XL), Y is a category digit, and ZZ is the specific fault within that category. Scan the QR code on the error screen, or just type help.prusa3d.com/en/{code} into a browser, and you land on an article explaining what happened and how to fix it. This article works through the codes that are documented for the XL specifically, drawing on the live articles at help.prusa3d.com rather than on the index page alone (which lists titles and codes but not the underlying troubleshooting text).
Because the XL shares its firmware lineage with the rest of the current Prusa lineup, a large chunk of its error codes are structurally identical to what you’d find on an MK4S or CORE One: USB and firmware-flashing failures, I2C bus errors, emergency stop, the Blue Screen of Death code, and so on all use the same category digits and the same wording, just with 17 swapped in for the printer prefix. What’s genuinely XL-specific is everything tied to hardware the other printers don’t have: the tool-changer and its docks, the segmented modular heatbed, and the “puppy” communication scheme that lets one mainboard talk to up to five separate toolhead (Dwarf) boards over MODBUS. Those are the codes this article spends the most time on.
Tool-changer, dock, and toolhead codes
The XL’s toolheads are picked up and parked using a carriage that rides the X gantry, and each tool has its own dock bolted to the rear extrusion. A lot of the XL’s unique error codes exist to catch problems in that mechanism before they turn into a crash.
Dock position out of bounds #17103 shows up when the Dock Position Calibration step (part of the selftest wizard) finds that a tool isn’t aligned where it expects. Prusa’s fix sequence starts with checking that the long metal profile holding the docks is pushed all the way to the left when viewed from the back of the printer, then retightening each dock with a 2.5 mm Allen key so it has zero play, then checking belt tension per the separate Adjusting belt tension (XL) article, and finally rerunning Dock Position Calibration from LCD Menu, Control, Calibrations and Tests.
Tool offset out of bounds #17104 fires during Tool Offset Calibration when a secondary tool’s offset relative to tool 1 falls outside the acceptable range. Since every other tool is calibrated against the first one, a bad tool 1 calibration can cascade into apparent failures on tools 2 through 5. Prusa’s article for this one is specific about mechanics: make sure the flexible cable-bundle plate moves in a straight line without binding, check that the nozzle isn’t sitting too low and hitting the calibration pin, and on single-tool XL units, hold the heater block (cold, unheated) and snug the set screw with a TX8 Torx key without overtightening.
XY probe unstable #17105 and XY position invalid #17106 both come out of the same XY-probing step inside Tool Offset Calibration. The first fires when repeated probes don’t agree with each other; the second fires when a probe reading is out of the allowed range entirely, which is Prusa’s way of stopping the nozzle from colliding with a neighboring parked tool. Both point to the same suspects: a calibration pin that’s loose or dirty, a dock sitting between its locked and unlocked positions, or a nozzle that isn’t seated correctly (or is bent) in the Nextruder.
Pin not reached #17107 means the calibration pin used during XYZ calibration wasn’t detected at all, which usually means it isn’t installed, or that filament residue or a loose loadcell reading interfered with the probing move.
Toolchanger error #17135 (shared with #36135 on the CORE One INDX) shows the message “Check all tools if they are properly parked or picked.” Prusa’s fix is to make sure the toolchanger carriage is free of debris and that no dock pins are bent, manually park the active tool if the error hits mid-print, and rerun both Dock Position and Tool Offset Calibration if it keeps recurring.
Calibrate dock from menu #17136 is more of a prompt than a hard fault: it just means dock calibration hasn’t been completed yet, and the fix is to run it from Control, Calibrations and Tests, Dock Position Calibration.
Toolchanger problem #17813 is specific to the multi-tool XL and fires during printing, not calibration, when the tool-changer tries to park a tool in the wrong spot and it collides with a tool that’s already docked. The article’s fix path includes manually parking the picked tool by sliding the toolchanger carriage to the right to disengage it, checking belt tension, and lubricating the three coupler pins on each tool, since a dry pin is a common cause of a bad pick or park.
Underneath the toolheads, each one carries its own Dwarf board handling the hotend heater, thermistor, fans, loadcell, and filament sensor for that tool. Dwarf error #17502 and #17503 are generic wrappers: #17503 in particular exists because the Dwarf board runs its own Marlin-derived firmware, and any Marlin-level error that doesn’t map to a dedicated XL error code gets surfaced through this one instead, so the fix depends entirely on the specific message text shown alongside the code.
Communication between the main XLBuddy board and each Dwarf board (plus the modular bed controller) runs over MODBUS, and Prusa calls each of these peripheral boards a “puppy.” Puppy error #17513 (“Puppy discovery error. No puppy found”) fires when none of the puppies answer the XLBuddy during startup discovery, and puppy error #17522 (“Waiting for puppies to start timed out”) fires when a puppy stops responding mid-operation. There’s a wider block of puppy error codes in the 17511 to 17522 range covering variations on the same discovery and timeout theme. The documented fix path for both codes above is the same: reflash firmware, then physically inspect the Nextruder cables at both the Sandwich board (tools 1 and 2) or XL-Splitter board (tools 3 through 5) end and the Dwarf board end, since a loose or damaged cable is by far the most common cause. Several users in the article comments report that simply unplugging and reseating the extruder cables at the motherboard resolved the error, and Prusa’s support team acknowledged that fix wasn’t yet folded into the official article as of this writing.
Separately, extruder error #17536 (“Extruder motor is not spinning on tool #”) is a newer and heavily commented-on issue: Prusa attributes it to increased electrical resistance at the Dwarf cable connector, caused by the cable cover holding the connector too tightly. The official fix is to update to firmware 6.2.0 or newer and remove the dwarf-cover-connector piece so the cable isn’t clamped as hard. In practice, a large number of users in the comment thread report that the fix that actually worked for them was cleaning the connector pins on both ends with isopropyl alcohol or contact cleaner, which isn’t currently part of Prusa’s own written steps.
The Selftest failed (XL multi-tool) article (which doesn’t carry its own single numeric code, since it wraps the whole calibration sequence) is worth reading alongside these: it walks through every step in order (fan test, X/Y axis test, Z alignment, dock position calibration, loadcell test, nozzle diameter confirmation, Z axis test, nozzle heater test, filament sensor calibration, tool offset calibration, bed heater test, phase stepping) and repeatedly points back to belt tension as the single factor most likely to cause failures across several of those steps at once. The single-tool XL selftest skips the dock and tool-offset steps, since there’s nothing to calibrate between toolheads.
Modular bed and Y-axis codes
The XL’s heatbed isn’t one continuous plate. It’s built from individually wired heatbed tiles (the exact count depends on print area size) driven by a modular bed controller board, which is a piece of hardware the MK4S, CORE One, and MINI+ simply don’t have.
Modular bed error #17256 (“Heatbed tile no. #: Preheat error,” internally named “MB heater disconnected”) fires when a specific tile fails to heat. The article has you check the tile for physical damage and reseat its cable at both the tile and the modular bed electronics. It also flags one XL-specific quirk: if the failing tile is number 1 or number 7, the cause is sometimes a faulty power supply rather than the tile or cable, since those two tiles sit closest to the printer’s two PSUs, and the article walks through opening the PSU cover to check for a lit status LED before you start swapping cables.
There’s a wider family of modular bed codes in this same range, including #17250 through #17257, #17301 through #17303, and #17319/#17320, all tied to different fault conditions on the bed (power failures, tile mismatches, and communication faults with the bed controller). Modular Bed Error #17319 specifically covers a hardware-detected power fault on the bed, shown as “Power failure,” and #17320 covers a related power-panic condition on the same subsystem. Prusa’s documentation for the less common codes in this range is thinner than for #17256, and this article doesn’t claim to have verified the fix text for every one of them individually.
Homing errors on the XL use the same naming as the rest of the current lineup: Homing error Z #17301, homing error X #17304, and homing error Y #17305. The Z homing error message specifically calls out the loadcell (“make sure the loadcell is working”), since the XL homes Z using loadcell contact against the bed rather than a physical Z endstop. Prusa’s fix steps for these are largely mechanical and shared in spirit with the MK4S equivalents: check for anything obstructing the axis, and rule out vibration from another printer running on the same surface, which the article calls out as a real and recurring cause of false loadcell readings on the XL given its larger, heavier gantry.
Power Panic #17321 is the XL’s detected-power-loss handling, distinct from the bed-specific power codes above; it’s part of the same “3” mechanics and power category as the homing and modular bed group.
Heating and extrusion codes
Temperature-category codes on the XL follow the same category digit and wording pattern used across the rest of the Buddy-firmware printers, just with 17 as the prefix instead of 13 (MK4) or 26 (MK4S).
Extruder preheat error #17202 (“Check the heater and thermistor wiring for potential damage”) fires when the nozzle can’t gain more than 2°C in 20 seconds after the heater is commanded on. Prusa’s fix is a cold, powered-off inspection of the connectors on the Dwarf board, followed by resistance checks on the thermistor (80 to 125 kΩ at room temperature) and heater cartridge (12.3 to 15.1 Ω), both measured with the printer unplugged.
Extruder thermal runaway #17204 fires if the nozzle temperature drops 6°C and doesn’t recover within 20 seconds during a print, and again points first at the heater and thermistor wiring on the Dwarf board.
Extruder Maxtemp error #17206 and extruder Mintemp error #17208 are the XL’s over-temperature and under-temperature cutoffs, and heatbreak Mintemp error #17211 and heatbreak Maxtemp error #17212 cover the same pair of thresholds for the heatbreak thermistor rather than the nozzle thermistor. Extruder temp not matching #17210 and heatbed temp not matching #17209 cover cases where the measured and expected temperatures diverge outside of a runaway event, generally pointing at the same wiring and connector suspects.
Hotend Heater Overcurrent #17322 is shown when the printer detects the hotend heater drawing more current than expected, which Prusa attributes to a damaged cable somewhere between the heater and the Dwarf board, or a damaged connector; each Dwarf connector has a small safety latch that has to be released before unplugging it, and forcing a connector without releasing the latch is called out as a way to damage it further.
Extruder error #17536, covered above under tool-changer codes because it’s fundamentally a connector-resistance problem tied to the Dwarf cable cover, is worth a second mention here since it presents as a motor fault rather than a heating fault on the printer screen.
Loadcell codes
The XL uses a loadcell on each toolhead, both to detect nozzle-to-sheet contact for first-layer and Z calibration and to protect the nozzle from digging into the steel sheet. Because there’s one loadcell per tool rather than one for the whole printer, loadcell faults on the XL are also implicitly per-tool.
Loadcell not calibrated #17523 (“Loadcell calibration is incomplete. Restart the printer and calibrate loadcell”) fires when the calibration step wasn’t completed or wasn’t recognized as complete; it’s resolved either through the full selftest or by rerunning loadcell calibration on its own from the printer menu. Loadcell tare error #17524, loadcell tare failed #17525, loadcell measure failed #17526, Loadcell Bad Configuration #17527, and loadcell timeout #17528 round out the loadcell error group; Prusa’s own Loadcell troubleshooting article (shared across the MK4/MK4S/XL/CORE One family, since they all use the same loadcell-based Z-homing approach) is the reference point for most of these, and the most commonly cited real-world cause across the group is vibration from the printer’s supporting surface, including a second printer running nearby, which the XL’s larger mass and gantry appear to make it more sensitive to than the single-head printers.
Chamber and enclosure codes
The XL, when built or upgraded with the official enclosure, measures chamber temperature and can shut a print down before heat buildup damages the printer. Chamber overheating #17260 and chamber temperature is critical #17261 are shared, code-for-code in structure, with the CORE One and CORE One L (as #31260/#17260 and #31261/#17261 respectively), which tells you this is a shared firmware feature rather than something built specifically for the XL. The documented fix for both is the same: set the enclosure fan to maximum from LCD Menu, Control, Enclosure settings, Manual settings, Fan rotation, and slide the bellows down to improve airflow. #17261 is the more severe of the two and aborts the print outright rather than just warning.
What’s shared with the rest of the lineup
A large share of the codes listed against the XL on Prusa’s own QR error code index are not meaningfully XL-specific: USB detection and overcurrent errors (#17602, #17603, #17604, #17306, #17307), firmware flashing and validation errors (#17605 through #17614), I2C bus errors (#17311 through #17318), ESP32/Wi-Fi errors (#17504 through #17506, #17533), emergency stop (#17510), out-of-memory (#17507), the Blue Screen of Death code (#17538), and Prusa Connect registration failure (#17401) all exist in near-identical form across MK4, MK4S, MK3.9(S), MINI, and CORE One, just with the printer’s own two-digit prefix substituted in. This article doesn’t walk through each of those individually since the underlying fault and fix are architectural, not specific to the XL’s hardware, and duplicating them here wouldn’t add anything beyond what’s already documented once, generically, in Prusa’s knowledge base.
Several XL toolchanger fault codes, including #17135 and #17136, are shared verbatim with the CORE One’s own INDX multi-tool variant. See the Prusa CORE One Error Code Index for the single-tool CORE One’s own five-digit error codes.