Fanuc alarm PS0090: REFERENCE RETURN INCOMPLETE
PS alarm (program/operation) · Fanuc 0i-D
What it means
Manual/automatic reference position return did not complete normally, typically because the start point was too close to the reference position or the return speed too low for one full servo revolution. With absolute-position detectors it can also mean the grid zero could not be established and requires the motor-zero reset procedure.
Likely causes
- Dog-to-reference gap smaller than one motor revolution
- G28/zero-return feedrate too slow (parameter 1428)
- Absolute pulse coder zero mark lost — needs power-off, motor rotation, and re-reference procedure
- Encoder battery dead causing reference loss
Triage note: If caused by APC battery loss, replace the pulse-coder battery pack and re-establish reference.
Need the part urgently?
Send us alarm PS0090 with your machine details — typical RFQ turnaround is 24–48h.