Elegoo Mars 5: Known Issues and How to Fix Them

The Elegoo Mars 5 is a 2024 resin printer that sells for $179: a 6.6-inch 4K mono LCD with a 35 µm pixel (4098 × 2560), a 143.43 × 89.6 × 150 mm build volume, up to 70 mm/h, a 405 nm COB light source, layer heights from 0.01 to 0.2 mm and 0.02 mm Z-axis accuracy.

This article covers the faults that belong to the base Mars 5 specifically, not to resin printing in general. Universal defects — delamination, under-exposure, cupping, elephant's foot — live in our resin print defect guide. Every fix below comes either from the official Elegoo wiki or from cases owners actually took apart and solved.

The short list: what actually breaks on a Mars 5

• Firmware. Power the printer on with a USB drive plugged in and you get a green "100%" filling the screen and a dead machine.
• USB drives. Only the bundled stick gets recognized; everything else reads as "no USB drive".
• File format. The Mars 5 reads .goo only, so .ctb files sliced for a neighboring model simply never appear.
• Leveling. The base model has no plate calibration in its menu at all, and "auto leveling" is a spring-loaded plate with a force sensor.
• Flex plates. Add a magnetic base and the printer throws "Foreign matter detected" on every home move.
• Electronics. The touchscreen reboots when the Z axis moves, the UV light refuses to turn on, the Z limit switch fails.
• The LCD. A resin leak kills it without warning, and replacement panels are out of stock for months at a time.
• Mechanics. The Z axis stutters because of the spring cable, the anti-backlash nut and a dry lead screw.
• Consumables. The film counter never resets itself, and the film wears out in patches.
• Expectations. 4K and 35 µm is not a defect — the older Mars 4 shipped with a 9K panel.

Stuck at "100%" after booting with a USB drive in

This is the most common — and most avoidable — way to brick a Mars 5. A green "100%" appears on the screen, sometimes prefixed with "V1.1", and the printer does nothing else. A variant of the same fault: the screen only lights up while a USB drive is inserted and stays dark without one. No hardware is broken. The Mars 5 has no Wi-Fi and no over-the-air updates, so firmware only ever installs from a USB drive at boot. Every power-up the printer reads the root of whatever stick is plugged in, finds update files there (or chokes on a flaky drive), starts flashing and dies halfway through.

1. Take an 8–16 GB drive and format it as FAT32 using a full format, not a quick one. Nothing else should be left on it.
2. Unzip the firmware and drop all three files into the root of the drive — no folder. The official instruction on the Elegoo download page reads: unzip all files into the root directory, insert the drive, restart the machine and it will read them automatically.
3. Boot with that drive in, wait for the flash to finish, then remove the drive and restart the printer once more — without that second reboot the update does not take effect.
4. Still nothing? Swap the drive. Owners regularly report firmware refusing to load from two or three sticks and going through instantly on a fresh, brand-name one. That is the bootloader being picky, not superstition.
5. The Mars 5 firmware file is not published on Elegoo's download page — only the manual and a test model are. The current build (the community passes around version 2.2.25 dated 12 June 2024; 2.2.29 from March 2025 is the newest anyone reports) and the recovery file ChituUpgrade.bin come from support at 3dp@elegoo.com.

The printer only reads the bundled USB drive

A familiar story: the first print ran fine from your own drive, and the next day the printer says "USB drive not inserted" and only cooperates with the stick from the box. USB is the only way files get into a Mars 5, so a fussy port stops everything. Elegoo's requirements are strict: FAT32, 16 GB or smaller.

1. Check the drive on a computer first. If the computer cannot see it, the drive is dead and nothing else matters.
2. Format it as FAT32 — right-click and Format on Windows, Disk Utility with MS-DOS (FAT) on macOS.
3. Use an 8–16 GB stick. 64 and 128 GB drives will happily format to FAT32 and still get ignored by the printer. Remember FAT32's own limit too: no single file above 4 GB.
4. Rename the file using plain characters with no spaces or symbols — Elegoo lists special characters in filenames as a direct cause.
5. Confirm the file is sliced to .goo. The printer will not print an STL and will not open a .ctb.
6. If nothing at all is recognized, the next suspects are the internal USB extension cable and the power PCB, then the mainboard. That is service territory — the steps are in the official Elegoo guide.

.goo only: the Mars 5 will not open a .ctb

Elegoo split file formats inside a single series: the Mars 5 Ultra reads both .ctb and .goo, while the base Mars 5 reads .goo alone. That is where complaints like "it prints for ten minutes then drops the file" or "the file just isn't in the list" come from. Check that your slicer profile says Mars 5 and not the model next to it.

Chitubox and Voxeldance Tango ship with the Mars 5 officially, alongside Elegoo's own free slicer SatelLite, which exports .goo by default. If you need another format, SatelLite carries a UVTools plugin — the project is alive, with its most recent commit on 20 August 2026. And to be clear: .goo is not a broken format, it is the sliced file itself. No resin printer prints an STL directly.

Anti-aliasing is hidden in the Chitubox profile

Open Chitubox with a base Mars 5 profile and the anti-aliasing setting is nowhere to be found, even though neighboring models have it. On a 35 µm pixel that matters: gentle slopes keep a visible pixel staircase that anti-aliasing partly hides. The setting has not gone anywhere — it is flagged as hidden inside the printer profile file.

1. Close Chitubox completely, otherwise it rewrites the file with its own settings on exit.
2. Find the working printer profile with the .cfgx extension and open it in a text editor.
3. On the anti-aliasing entry, change "visible": false to "visible": true and save.
4. Restart Chitubox and the option appears in the settings panel. The trick was documented by an owner on Chitubox 2.2 beta.
5. Don't want to touch files? Slice in Lychee instead — owners report anti-aliasing working there for the Mars 5.

There is no plate calibration in the base Mars 5 menu

You notice that prints come out as smooth, polished rafts, supports never rise, half the plate refuses to stick — so you go looking for the leveling menu. It isn't there. The Calibration entry on a Mars 5 is an exposure test, not leveling, and there is no Save Z=0 button either. "Auto leveling" here works like this: a spring-loaded plate descends until a force threshold trips, and that fixes the print start height. Start height, yes — parallelism to the LCD, no. That is held by four screws on the plate and nothing else.

1. Remove the vat and the UV cover, then wipe the LCD — not a drop of resin or a single cured fleck should remain on it.
2. Loosen the plate lock, pull the cap and back off the four hex screws on top of the plate so it floats freely.
3. Send the plate home via Tool → Manual → Return to home. Remember that "home" is where the limit switch trips on the lead screw, not your print zero.
4. Slide a sheet of ordinary paper under each of the four corners and tighten the screws evenly, in a cross pattern. All four sheets should drag with the same resistance.
5. Verify with a test print. The Peg of Calibration model shows plate tilt against the LCD immediately.
6. Need more time to tighten? Slice a file with a 120-second bottom exposure and adjust the screws while it cures. Mars 5 owners push that to five minutes when the first attempt misses.

Flex plates and the endless "Foreign matter detected"

A magnetic base with a spring steel sheet is the first upgrade most resin owners buy — prying models off a rigid plate with a scraper is awkward and hard on the prints. Install one on a Mars 5 and the printer starts throwing "Foreign matter detected, please troubleshoot" on every home move and every auto-level. The reason is straightforward: base plus sheet raise the surface by a few millimeters, the force sensor trips earlier than expected and reads that as an obstruction. One owner measured the difference at 3.2 mm.

1. Stick the base down and immediately re-level the plate by hand, following the procedure above, with the sheet already installed.
2. Confirm on the first layer that the plate is not crushing the LCD: the raft should release with effort but must not come out polished.
3. From here there are two routes. Mars 5 Ultra owners simply dismiss the warning and force the print — that works on the base model too, provided you leveled it properly.
4. The second route is a file that rewrites the zero height. Elegoo published one for the Mars 5 Ultra (m5uchitugcode.gcode, on the abnormal noise page) but never for the base Mars 5. One base-model owner solved it with a .goo file supplied by flex plate maker Wham Bam, whose compatibility list names the Mars 5 directly.
5. Any such adjustment has to be reapplied after every firmware update — it lives in the machine settings, not on your drive.
6. Expect one side effect: with a new zero height the first layers get noticeably louder. That is normal.

"Resin exceeded maximum limit" with a normally filled vat

The printer refuses to start and reports too much resin in the vat, while the level sits below the MAX line. No level sensor is involved — the Mars 5 does not have one. It reads level with the same force sensor that drives auto leveling: the plate descends and the machine catches the moment it touches the surface. Any extra free play in the plate assembly therefore reads as "too much resin".

1. Check the plate lock first. In the overwhelming majority of cases it simply was not clamped down — this is the single most common cause.
2. Snug up the vat screws: not brutally tight, just enough that the vat does not shift.
3. Confirm the resin really is below the MAX line and pour the excess back through a filtered funnel if it is not.
4. Power cycle the printer from the switch and start the print again.

The touchscreen reboots when the Z axis moves or the LCD fires an exposure

The screen blanks and restarts at the exact moment the Z axis starts moving or exposure kicks in. Elegoo dedicates a wiki page to this fault on the Mars 5, and it lists four causes: a defective power adapter, a loose ribbon on the mainboard, a short on the constant current board and a loose earth wire. Work through them from simplest to hardest.

1. Measure the adapter output — it should hold a steady 24 V. Then connect a different 24 V adapter and run Tool → Calibration → Confirm. If the reboots stop, the adapter was the problem.
2. Power everything down and remove the six rear cover screws and six right side panel screws with a 2.0 mm hex key (other sections mention seven screws — that is a different panel and a different teardown). Re-seat the connectors marked in the guide.
3. Peel back the tape at the touchscreen and the LCD, lift the clip and re-seat both ribbon cables.
4. Unplug the constant current board cable and run the exposure again. No reboots means that board is shorting and needs replacing — service part number A0M011.
5. Check the earth wire: a loose ground gives exactly the same symptom.

The Z axis will not lift, or moves in jerks

You start a print and the plate does not respond, or crawls up against resistance; manual jog commands do nothing either. Elegoo lists five causes for the Mars 5, and three of them take ten minutes with no soldering: a folded spring cable, loose motor screws and a dry lead screw. The remaining two are a damaged anti-backlash nut and a loose motor connector.

1. Take off the UV cover, the plate and the vat so you can see the whole axis. Power down and straighten the spring cable if it has folded, kinked or snagged on anything. Do not squeeze or puncture it.
2. Power up and jog the axis through Tool → Manual → step size → up and down arrows. If it runs smoothly now, stop here.
3. Check the two screws on top of the Z motor and tighten them with a 2.5 mm hex key if needed.
4. Wipe the lead screw and the rail with a lint-free cloth and apply fresh white lithium grease — a dry screw is exactly what produces the jerking.
5. Loosen the anti-backlash nut screw and test the travel. If the axis frees up, the nut needs replacing; tighten the screw back afterwards either way.
6. Remove the seven rear cover screws with a 2.0 mm hex key, cut the cable tie on the spring cable, pull two extra coils out and secure it with a fresh tie. Mind the cable itself when you cut.
7. Take off the right panel (three 2.5 mm screws on top, three 2.0 mm below) and inspect the motor connector. The factory fixes it with hot glue — if the connector is intact, leave the glue alone.

The plate does not stop at the top and hits the frame

During self-test the plate keeps climbing and jams against the top of the Z axis. The limit switch is at fault: either dust and cured resin have collected in its trigger area, or a connector is loose, or the switch itself (or its cable) has failed. Elegoo also documents a safe way to test this instead of letting the axis slam blindly into the frame.

1. Power down, remove the UV cover, plate and vat. Turn the lead screw by hand to bring the carriage to the bottom — the screw is greased, so wear gloves or hold it through a cloth.
2. Lay the printer on its side and remove the four top cover screws with a 3.0 mm hex key.
3. Clean the switch trigger area with a lint-free cloth dampened with 75% isopropyl alcohol — a single cured drop of resin is usually the whole problem.
4. Tighten the switch mounting screws with a 2.5 mm hex key and inspect the connector. It is glued too, so an intact connector stays as it is.
5. Reassemble and run self-test. Before it reaches the "Z-Axis-motor-status" step, hold something in the trigger area and confirm the axis stops. If it does not, kill the power right away.
6. Beyond that, remove the seven rear panel screws with a 2.0 mm hex key and check the switch connector on the mainboard side. A scorched or resin-soaked connector is your cue to stop and contact support.

The UV light never turns on and the print cures nothing

The printer runs the entire job and there is not one cured layer on the plate or in the vat. The test is quick: run an exposure test and look at the LCD. If the pattern is there but nothing glows, the UV array is not firing. On the Mars 5 the first and most frequent cause is the wrong power adapter.

1. Flip the adapter over and read the label. The Mars 5 needs 24 V at 3 A. Most adapters from Mercury wash and cure stations output 12 V — the printer wakes up on them, but the UV light stays dark. When two similar bricks sit side by side on a bench, they get swapped constantly.
2. Measure the output with a multimeter, or plug in another 24 V adapter rated at 3 A or more with the same barrel connector.
3. Power down and remove the seven rear panel screws with a 2.0 mm hex key. Check the three UV array connectors marked in the official guide.
4. If you have a multimeter, measure voltage at the UV ports during the exposure test (Tool → Calibration → Confirm). No voltage points at the constant current board and the mainboard — that is a service case.

Resin leaks under the LCD and kills it

The most expensive failure on a Mars 5. The panel is covered only by a PET scratch film, with a thin gasket frame running round the perimeter. A spill tears that gasket loose and resin goes inside. Symptoms vary: "Hardware Failure. Please Troubleshoot" during self-test, a puddle around the printer, a faint or partial pattern in the exposure test, dead pixels, lines, flicker. It can also happen silently — one owner's machine kept "printing" while nothing stuck to the plate or the film, because resin under the panel had cured and glued it from the inside.

1. Run the exposure test and inspect the panel surface closely. Cracks together with dead pixels mean replacement, full stop.
2. Check the ribbon cable at both ends. It is marked: the LCD or SCREEN side faces the panel, the MB side faces the mainboard. A ribbon fitted backwards gives you a black screen, indistinguishable from a dead panel.
3. Update the firmware — an outdated version is on Elegoo's own list of causes.
4. If resin got under the panel, the LCD is done. The genuine part costs $39.99 from Elegoo, but stock is unreliable: owners describe waiting months.
5. The only official Mars 5 replacement instruction is an Elegoo Official video — there is no wiki article for it. Neighboring service part numbers, for reference: mainboard A0M081, touchscreen A0M0C1, constant current board A0M011.

The film counter demands a replacement the moment you fit a new film

You fitted a new film and the printer still warns that its life is used up before every print. Nothing is broken: the Mars 5 has no way to tell a fresh film from an old one, it simply counts layers. Owners of this Elegoo generation report a default threshold of 60,000 layers, and after a replacement you reset that counter by hand.

1. Open the device self-test on the printer's screen.
2. Find the release film usage counter and tap the round reset button next to it.
3. Treat the threshold as a reminder rather than a verdict: some owners run past 100,000 layers on one film, others tear one much sooner.
4. Judge with your eyes and fingers instead: dents where models stood, cloudiness, lost tension. A healthy film answers with a short, drum-like note.

The film wears out in patches from repeated layouts

The Mars 5 vat is fixed, so the model peels vertically, across its whole footprint at once. Which means the film stretches exactly where the parts sit. One owner running the same miniature layout plate after plate hit mass failures on the seventeenth full plate, with the film still looking intact. For contrast, owners of machines with a Tilt Release vat report passing 300,000 layers on one film.

• On production runs, shift the layout from plate to plate — if this batch printed on the right, put the next one on the left.
• Check film tension by sound and feel every couple of dozen prints, not by the counter.
• Raise the lift distance and lower the lift speed so the film has time to release and fresh resin can flow underneath.
• Dents or cloudiness in the print zone mean replacement now, regardless of the counter. A tear costs you the LCD.
• Buy spare films in multipacks — they are consumables and one spare on the shelf is always worth it. Compatible sheets turn up under a search for Elegoo Mars 5 FEP film.

Loud peel snaps and prints stuck to the vat: cold resin

The Mars 5 has neither a heated vat nor a tilt mechanism, which makes it markedly more sensitive to resin temperature than its bigger siblings. Elegoo's recommended range is 25–30 °C. Below 25 °C in the room, warm the bottle first: about ten minutes standing in roughly 60 °C water. Sharp snapping during peel and models glued to the bottom of the vat are the first sign that resin is too viscous or the cross-section is too large.

1. Warm the resin and do not start below 20 °C in the room. Experienced Mars 5 owners wait for 25 °C.
2. Rotate the model 30–45° so the cross-section changes gradually. This single step fixes more failures than any setting.
3. Cut exposure — both bottom and normal layers — using the table for your resin. Elegoo's official numbers for the Mars, Saturn and Jupiter series live in a shared parameter sheet, and the exact figure for your bottle comes from the Cones of Calibration test. Ignore the label on the bottle — those numbers were written for older machines.
4. Increase the wait after release by roughly 20 seconds on problem models. The layer stabilizes and peel stress drops.
5. Set the layer height to 0.05 mm: very thin layers make separation harder, not easier.
6. Drop the light intensity (PWM) by 10%. The scale runs 0 to 255, where 255 is roughly 100% output.
7. The Elegoo Mini Heater fits the round port at the rear left and does work, but it has no temperature control: owners report it overheating the resin until edge supports start dropping off. Most settle on 21–23 °C as comfortable.

Prints fail at exactly the same height every time

A distinct case that is easy to mistake for a settings problem: every model on the plate breaks at the same layer, swapping film and resin changes nothing, and the same file prints fine on another machine. On a Mars 5 that is almost always Z-axis mechanics or a bad drive, not exposure.

1. Re-slice the file and write it to a different USB drive. A bad sector landing at that exact point in the file produces precisely this pattern.
2. Confirm the plate is clamped fully and does not sag under load.
3. Wipe the lead screw with a lint-free cloth and apply fresh grease. Contamination on one stretch of the screw stalls the plate at the same height every time.
4. If it still fails at the same layer, work through the official Z-axis procedure from the section above.

Resin spilled into the Z-axis channel and the plate seized

On the Mars 5 the lead screw and rail run exposed above the vat, so any spill lands straight on the mechanics. One owner whose plate stopped returning home after a failed print found exactly that: someone knocked the tent the printer stood in, resin reached the Z-axis channel and cured there. Power cycling will not help until the assembly is cleaned.

1. Power down, remove the plate and vat, and pour the resin back through a filtered funnel.
2. Dissolve the cured resin with isopropyl alcohol, stripping the old grease off the lead screw and rail completely.
3. Apply fresh white lithium grease and run the axis by hand through its full travel.
4. Only then reconnect power and run the self-test.
5. If resin reached the inside of the stepper motor, do not power the machine on at all — photograph it and contact support.

The vat thumbscrews snap off

A small thing that ruins a week: the thumbscrews clamping the vat to the chassis shear off inside their seats. One Mars 5 owner stripped the thread in the housing while digging a broken screw out. Elegoo does not sell that part separately in the store.

• Do not overtighten. The vat should sit firmly but without force — overtightening on every install is what shears these screws.
• Keep the threads clean; cured resin in the thread makes you turn harder than you should.
• Extract a broken screw carefully so you do not strip the housing thread — a stripped thread means replacing the whole front assembly.
• Ask support at 3dp@elegoo.com for the part. Under warranty, owners have been sent a full set.

Accessories: one mounting port and a wash station your plate won't fit in

Plenty of owners mistake the round opening in the Mars 5 lid for an exhaust port and try to duct it. It is not an exhaust — it is a mounting port for accessories, either the Mini Heater or the Mars Mate air purifier. There is exactly one, so you cannot run both. Elegoo's own spec sheet for the Mars 5 spells it out: "USB connection unavailable, compatible with Mars Mate" — the printer does not power the purifier.

• Pick one device for the lid and power the other from its own adapter.
• Ventilate the room or the tent as a whole, not through the lid opening. Resin fumes are not a cosmetic issue — we cover it in the fumes and ventilation guide.
• The Mercury Plus V2 wash station works with a Mars 5, but the Mars 5 plate does not fit inside its bucket: you have to pop models off the plate before washing and clean the plate separately.
• LCD protector films from marketplaces frequently arrive smaller than the panel even when the listing says "for Mars 5". Measure before you peel the backing.
• Washing and post-curing procedure is the same across every resin printer — it is laid out in our wash and cure guide.

Not a defect: 4K instead of 9K

One whole category of "problems" is really mismatched expectations. The "bigger number means better panel" logic breaks down here. The 2023 Mars 4 shipped with a 9K panel, the Mars 5 Ultra has 9K and an 18 µm pixel, and the base Mars 5 has 4K and a 35 µm pixel. That is model positioning, not a faulty or blurry screen — and it is why owners see a pixel staircase on gentle slopes and read it as a defect.

• Angle the model so the staircase does not land along a large visible plane.
• Drop to a 0.03 mm layer on detail-critical parts — vertically the Mars 5 is limited by 0.02 mm Z accuracy, not by the panel.
• Enable anti-aliasing if you are willing to edit the Chitubox profile (see the section above).
• If you need maximum miniature detail, that is a 9K job: the Mars 5 Ultra runs 8520 × 4320, 18 µm and a 153.36 × 77.76 × 165 mm volume against 143.43 × 89.6 × 150 mm on the base model.

Mars 5 message reference: what it means and what to do

The Mars 5 has no numeric error codes — it prints plain-text messages, in English or Chinese, the only two interface languages it supports. Here are the ones owners run into most.

Common resin printing problems

Beyond the Mars 5 specifics above you will meet the ordinary difficulties of resin printing — the same ones on Elegoo, Anycubic, Creality and everything else. Each has its own deep dive:

• Delamination, under-exposure, elephant's foot, cupping blowouts — resin print defects and how to cure them.
• First print, choosing a resin, handling safety — the beginner's guide to resin printing.
• Washing, drying and UV post-curing — the wash and cure guide.
• Smell, fumes and room ventilation — our piece on fumes and health.
• Sanding, priming and painting finished models — the post-processing guide.
• Where to find models worth printing — a roundup of 3D model libraries.
• What a single print actually costs — 3D printing cost calculation.

Sibling Elegoo machines built on the same spring-loaded "auto leveling" logic have their own write-ups: Elegoo Saturn 4 known issues and the Saturn 4 Ultra with its tilting vat. Cross-shopping the Mars 5 against its closest rival? See the weak points of the Anycubic Photon Mono 4.