Current to the cell is extremely low in both directions. Jandy says: clean or replace the cell and check the DC cord.
Extremely low cell current — often a worn cell. Check the cord and scale first; most 123s end in a replacement.
Code 123 means extremely low current to the salt cell in both directions. It usually means the cell is worn out, though a bad DC cord or heavy scale can cause it too.
Current to the cell is extremely low in both directions. Jandy says: clean or replace the cell and check the DC cord.
Use a strip. Under 3.0 gpl or water below 51°F can drag current down hard.
Confirm salt and temperature first.
Don't trust the board's salt number if the sensor is dirty. Use a strip or a meter. Target is 3.0-3.5 gpl. Cold water below 51°F stops chlorine production. Fix salt or temperature first, then recheck.
Power off. Check the DC cord for corrosion, a loose fit, or burn marks.
Inspect and reseat the DC cord.
Power off. Unplug the cord at the cell and inspect pins and socket. Corroded, blackened, or loose connections cause extremely low current readings. Clean light corrosion; replace a burned cord.
Heavy scale can cause 123. Hose first; acid only if needed. Follow the manual mix.
Clean the cell.
Try a hard stream from a garden hose first. If scale stays, pull the cell, plug the ports, and use Jandy's mix: 1 pint muriatic acid into 2 quarts water. Let it foam until it stops; don't soak for hours. Rinse well. Don't put the sensor in the acid.
Remove the pin cover. Loose or corroded pins, or plates eaten away from the studs, mean the cell is done.
Inspect cell pins and plates.
Remove the cover plate over the cell's power pins. Each pin should be tight to its plate. On a 123, plates often have corroded away from the pins — that's end of life, not something cleaning will fix.
Power up and watch a full polarity cycle. If 123 returns, plan on a new cell.
Clear and retest.
Power back up and let it run through forward and reverse. If 123 stays gone after a clean cell and good cord, recheck in a week. If it returns quickly with good salt and warm water, replace the cell.
123 with a clean cord and good water conditions usually means a worn-out cell.
Replace the cell.
Jandy's corrective actions for 123 are clean or replace the cell and check the DC cord. When cleaning and the cord don't clear it, replacement is the fix. Codes 124, 126 or 127 point to power/board issues — call a pro.
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When everything else checks out, the cell is worn.
When 123 persists after salt, temperature, cord and cleaning check out, the cell's plates are typically worn and replacing the cell is the fix.
Not a safety emergency, but chlorine output is near zero. Test and add liquid chlorine until it's fixed.
Often yes, after you've ruled out salt, temperature, the DC cord and scale. Jandy lists clean or replace the cell plus check the cord.
120 is low current forward, 121 reverse, 123 extremely low in both directions.
Yes if you maintain chlorine another way. The salt system isn't producing meaningfully until 123 is cleared.
Source: Jandy AquaPure/PureLink Power Center and Cell Kit, Installation and Operation Manual (H0325600), Section 7.2 Service Codes, Section 6.3, Section 9.3. Written by a Florida pool service owner. Updated 2026-10-14.