This guide explains what a gutter fault is, why it happens, and how to test, clean, and reset your CIJ printer to restore normal operation.
What is a gutter fault—and why it matters
In a CIJ (Continuous Inkjet) system, the gutter is where uncharged ink drops are recycled back into the printer. If the gutter is blocked, misaligned, or its sensor fails, the printer can’t confirm ink is flowing correctly—and it stops printing to avoid mess or damage.
The CM750 flags this issue with a gutter fault warning (yellow magnet icon), and if ignored, can escalate to full system halt.
Common causes of gutter faults
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Ink build-up in the gutter tube or nozzle return
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Gutter sensor misalignment or failure
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Disconnected or damaged sensor wiring
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Blocked or restricted return line
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Dirty or dried ink inside the gutter channel
How to fix a gutter fault
✅ Step 1: Visually inspect the gutter
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Power down the printer
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Use a lint-free cloth and approved cleaner
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Remove any dried ink or debris
✅ Step 2: Check the sensor
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The gutter sensor should be flush and aimed correctly
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Wipe it clean and ensure it’s not covered in dried solvent or ink
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If possible, trigger the sensor manually to test its response
✅ Step 3: Inspect connections
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Check that all wires to the sensor are secure
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Look for broken pins, corrosion, or loose terminals
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Use a multimeter to verify continuity (if trained to do so)
✅ Step 4: Reset the fault
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Power the printer back on
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Go to
System > Fault Log -
Clear or acknowledge the fault
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Re-start ink flow and test print
Prevent gutter faults in the future
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Clean the gutter and sensor weekly as part of routine maintenance
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Always run Drain and Fill Mixer before extended shutdowns
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Use only compatible Needham inks and avoid mixing fluids
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Train operators to clean heads and gutters as part of shift start-up
Still having issues?
If the gutter fault returns after a reset:
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Replace the gutter sensor module
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Check the return ink line for internal blockage
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Contact Needham technical support for further diagnostics