Industrial Robot Troubleshooting: Causes & Fixes

Not your exact symptom?

Describe it in the symptom finder and search the whole directory.

Problems on this page:

Positioning drift / inaccuracy Faulted axis / servo fault Dropped part / misgrip Overheating or overload fault Collisions after program changes Cable and dress pack wear Encoder battery or position memory alarms Cycle time creeping up Grease leaks at the joints

Positioning drift / inaccuracy

Hits OEE: Quality

Symptoms: Parts placed off-target, missed picks, quality rejects creeping in.

Worn gearbox or encoder

Check repeatability test; service the affected joint; replace encoder if faulty.

Loose or worn tooling (EOAT)

Re-tighten and inspect the end-of-arm tool; re-master if moved.

Thermal drift

Allow warm-up; enable thermal compensation if available.

Recovery after a collision

Re-master/calibrate the robot zero position.

Prevention: Periodic repeatability checks, EOAT inspection, warm-up routine.

Faulted axis / servo fault

Hits OEE: Availability

Symptoms: Robot e-stops with an axis/servo alarm, will not move.

Mechanical overload or collision

Clear the obstruction; check for damage; reset and re-master.

Encoder or cable fault

Inspect dress-pack cabling for wear; replace damaged encoder cable.

Brake not releasing

Check brake supply and wiring; test brake release.

Overheated servo / drive

Check cooling and duty cycle; clear the thermal fault.

Prevention: Dress-pack inspection, collision detection tuning, cooling checks.

Dropped part / misgrip

Hits OEE: Performance

Symptoms: Gripper drops or fails to pick parts, cycle interruptions.

Vacuum loss / air leak

Check vacuum level, cups and lines; replace worn suction cups.

Worn or misadjusted gripper

Inspect fingers/jaws; reset grip force and position.

Part presentation variation

Stabilise incoming part position; check feeder/fixture.

Mis-taught pick point

Re-teach the pick/place positions.

Prevention: Vacuum monitoring, gripper inspection, consistent part presentation.

Overheating or overload fault

Hits OEE: Availability

Symptoms: Axis overload/overheat fault, slowdowns, stops mid-cycle.

Payload or speed above limits

Verify payload/inertia and speeds; stay within rating.

Mechanical binding or worn gearbox

Check joints/gearboxes for binding and wear.

Cooling or duty-cycle issue

Check fans/cooling; review duty cycle.

Prevention: Payload/speed within spec, joint maintenance, cooling checks.

Collisions after program changes

Hits OEE: Availability

Symptoms: The robot hits fixtures or parts after an edit or a tooling change.

Edited paths not checked at low speed

Run every edited path at reduced speed before production.

Tooling changed without updating the program

Update tool data whenever tooling changes.

No interference zones

Set interference zones and collision detection.

Prevention: A change procedure for robot programs.

Cable and dress pack wear

Hits OEE: Availability

Symptoms: Intermittent signal faults, worn hoses and cables on the arm.

Dress pack rubbing on the arm

Reroute and protect the dress pack.

Twisting beyond the dress pack's range

Limit axis rotation or fit a suitable dress pack.

No cable management

Add retraction and supports.

Prevention: Dress pack inspections on a schedule.

Encoder battery or position memory alarms

Hits OEE: Availability

Symptoms: Battery warnings, lost position after a power cycle, mastering needed.

Encoder batteries low

Replace batteries the way the maker says, usually with power on, so position is kept.

Backup battery in the controller low

Replace the controller backup battery.

Position lost

Remaster the robot as the maker describes.

Prevention: Battery changes on the maker's schedule.

Cycle time creeping up

Hits OEE: Performance

Symptoms: The robot cell gets slower over weeks without a clear fault.

Speed overrides left reduced

Check speed overrides after maintenance and teach.

Waiting for signals

Find interlocks the robot waits on and fix slow sensors.

Paths not optimised after changes

Review and smooth the paths.

Prevention: Cycle time trended per cell.

Grease leaks at the joints

Hits OEE: Availability

Symptoms: Grease around the axis seals, noise from a joint.

Greasing intervals missed

Follow the maker's greasing intervals.

Worn seals

Replace the seals.

Joints overfilled

Grease with the amount and method the maker gives.

Prevention: Greasing on the maker's schedule, with records.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Alarm codes: Epson robots error codes · Yaskawa Motoman alarm codes · FANUC robot (SRVO) alarm codes · ABB robot (IRC5) error codes

Related equipment guides: pick and place · palletizer · depalletizer · overhead crane · laser welding machine · tyre curing press · safety light curtain

Stop the same fault coming back

Recurring industrial robot stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

Book a Fabrico demo

The directory stays free.

Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover