Jackson Glasswasher Error Code F12: Booster Probe
F12 on a Jackson Delta HT-E-SEER glasswasher means the booster temperature probe has failed. The manual's one action is to replace the probe that connects to P13. A technician should do it.
High: without a working booster probe the final rinse temperature cannot be controlled.
- Code
- F12
- Maker
- Jackson
- Equipment
- Glasswashers
- Applies to
- Delta HT-E-SEER glasswasher dishmachines
What does Jackson error code F12 mean?
F12 covers the booster side of the probe pair. The booster probe, T3, lets the control judge how hot the final rinse is, and when it decides that probe has failed, the screen shows "F12 Service needed - check booster thermostat". The manual lists one cause, a failed temperature probe (T3), and one action, to replace the probe that connects to P13. As with F11, the entry stands alone: no contactor, IO module or heater is listed. The final rinse is what leaves glassware bright and sanitized, so a booster probe that cannot be trusted undermines that step. The manual does not describe what the machine does while F12 is shown and does not give a resistance value for the probe. It is a short, direct instruction that the control gives to the technician.
Affected models and control systems
Jackson Delta HT-E-SEER glasswasher dishmachines. The error table is on printed pp. 25-27 of the Delta HT-E-SEER manual.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- Display reads F12 Service needed - check booster thermostat
- Booster temperature reading wrong or missing
- Rinse that seems cooler or hotter than usual
Possible causes
Listed in Jackson's documentation
- Booster temperature probe (T3) failed
Other likely causes — what usually sits behind error code F12 on this control. A technician confirms which one it is before any part is replaced.
- A probe that has aged in the hot, wet booster tank
- A lead that was pinched during a cabinet clean
- A P13 connector pin that no longer grips
Safe checks before calling for service
- Turn the glasswasher off and on once and see whether F12 returns.
- Do not touch the probe or open the cabinet.
- Note whether the final rinse looks normal.
- Give the technician the exact screen text and the model name.
How a technician diagnoses error code F12
- Confirm F12 and that the probe connects to P13.
- Inspect the lead and plug at P13.
- Measure the probe resistance against the manual's table.
- Replace the probe connected to P13.
- Run a booster heat-up and confirm the reading tracks the water.
- The probe connects to the IO module, a live board.
- The booster tank holds hot water that can scald during probe removal.
- A resistance check is needed to prove the probe is the failed part.
How error code F12 differs from similar codes
F12 is the booster probe, and F11 is the wash probe. F2 and F5 also list the booster probe, but with other possible causes.
Technical reference
- Document
- Delta HT-E-SEER Installation, Operation, and Service Manual
- Edition
- 07610-004-54-86-E (Rev E)
- Models / control
- Delta HT-E-SEER glasswasher dishmachines
- Section
- Fault Codes / Troubleshooting, printed pp. 25-27 (PDF pp. 32-35)
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related Jackson glasswasher error codes
How is F12 different from F2?
F12 says the probe has failed. F2 says the booster heater stays on, with the probe as one of three possible causes.
Do all Jackson machines show F12?
The DynaTemp door-type manual lists F12 as Not Used, so it depends on the model. On the Delta HT-E-SEER it is the booster probe.
Can I use the machine meanwhile?
The control cannot read the final rinse temperature reliably, so we advise waiting for the repair.
Need help with Jackson error code F12?
A technician confirms the cause on site and gives you the price in writing before any work starts.