Jackson NXP dishwasher Error Codes
Applies to: NXP door-type dish machines. Compiled and paraphrased from the Jackson NXP-HTD Installation, Operation and Service Manual, document 07610-004-91-86-D, published by Jackson WWS. Resistance values and setpoint ranges are Jackson's published figures. Confirm against the manual for your model. Table last updated Aug 13, 2026.
How to read the codes
Jackson calls these dish machines and most kitchens call them dishwashers; the codes are the same either way. Jackson's NXP display shows a code AND a plain-language second line, so F3 reads 'F3 No water in wash tank' followed by 'Check inlet water and door'. Read both: the second line often names the fix. The codes pair up, one set for the BOOSTER and one for the WASH TANK, so F1 and F6 are the same fault in different tanks, as are F2 and F7, F4 and F9, F5 and F10. Knowing which tank a code refers to tells you which probe and which heater to look at.
The codes
| Code | Meaning | Likely causes | Operator-safe steps | Technician work |
|---|---|---|---|---|
| F3 / F8, no water in wash tank, check inlet water and door | The machine could not fill | Jackson lists the door FIRST: an open door inhibits fill mode. Then a faulty door switch, or a fill solenoid or fill relay fault | Close the door properly so the door switch activates. This is the code most often cleared without a call, and the display tells you to check the door | Door switch replacement or adjustment, then fill solenoid and fill relay |
| F1, no water in booster | The booster is calling for heat with no water in it, which the control blocks to protect the element | Low or no water pressure, faulty pressure switch, faulty inlet valve or fill relay, or a float switch letting heaters run dry | Check the water is on and the supply is not throttled. Jackson specifies 10 PSI plus or minus 2 FLOW pressure, which is not the same as static pressure | PSI check, pressure switch, fill relay voltage to the solenoid, then float switch. Substituting a 1.2k resistor for probe T3 should turn the booster heater off; if not, the IO module is at fault |
| F6, no water in wash tank | Same fault as F1 but on the wash tank rather than the booster | Low or no water pressure, faulty inlet valve or fill relay, welded wash heater contactor, or a float switch letting heaters run dry | As F1, check supply pressure first | Same sequence using probe T1 instead of T3 |
| F2 / F7, check booster or wash tank thermostat | A heater contactor is not switching off when it should | Welded contactor contacts, a faulty temperature input on the IO module, or a faulty probe | Nothing at operator level. A heater that will not switch off is a scald and damage risk, so report it rather than working around it | Check for welded contacts first, then verify the IO module output turns off above set temperature, then the probe against the resistance table |
| F5 / F10, check thermostat and high limit | The tank is not reaching temperature | Faulty temperature input, faulty probe, faulty high-limit switch, faulty heater, or a contactor not energising | Expect a rinse below 180F, which is a sanitising failure rather than a cleaning one. Do not run the machine on and assume the dishes are safe | Substituting a 1.8k resistor for the probe should turn the heater on; if not, replace the IO module. Then probe, high limit, heater resistance, and contactor drive voltage |
| F4 / F9, check incoming power | The machine is not receiving power correctly | Incoming power not properly connected, or L3 missing on a three-phase machine | Check the breaker has not tripped. If it trips again, stop and call an electrician rather than resetting repeatedly | Heater connections and confirmation that L3 is present. Jackson notes the imbalanced wild leg goes to L3 |
| F11 / F12, check wash tank or booster thermostat | A specific probe has failed | Faulty temperature probe. F11 is the probe at P10, F12 the probe at P13 | No operator action | Replace the named probe; Jackson identifies them by connector so no guessing is needed |
| F13, communication error, check 6-pin cable | The display board and the IO module have stopped talking | Loose or faulty 6-pin cable between display and IO module, or a failed communication port at either end | No operator action, but worth reporting if the machine has been moved or serviced recently, because this is a connector fault | Fully disconnect and reconnect the 6-pin cable at BOTH ends until a click is heard, then check for a broken wire by gently pulling each conductor. Substitute a known good display board, then a known good IO module |
| F14, check incoming water pressure or pressure switch | The machine is not seeing the water pressure it needs | Low or no water pressure, faulty pressure switch, or a fill valve not receiving power | Check nothing upstream has been turned down. Jackson's requirement is 10 PSI plus or minus 2 flowing | PSI check, pressure switch, fill valve continuity |
| F15, Sanisure violation | The machine could not meet its sanitising requirement | Faulty booster heater or faulty heater contactor | Treat this as a food safety event, not an inconvenience. The rinse did not reach sanitising temperature | Check heater amperage, then contactor coil voltage and both L1 and L2 legs |
| F16, LLC violation | A low liquid level control fault | Faulty or corroded probe | No operator action | Clean or replace the probe |
| F17, excessive inlet temperature | The incoming water supply is too hot | Building hot water set higher than the machine expects | This is a plumbing setting rather than a machine fault. Jackson's inlet requirement is 110F | Verify supply temperature and adjust the water heater or add tempering |
| Reading probe resistance | How to confirm a probe rather than replacing it on suspicion | A drifting probe misreports temperature without raising a code | If wash or rinse temperatures look wrong but no code shows, ask for the probes to be checked against the table | Jackson's values run 11.58k ohms at 69.8F, 3.05k at 140F, 1.58k at 179.6F and 0.96k at 212F. Setpoint ranges are 150 to 170F wash and 180 to 192F rinse |
If this needs a dish machine technician
5 companies in this directory name Jackson on their own site: that page shows who has been phone-confirmed, who publishes 24/7 cover, and what each puts in writing. Start there if the brand matters more than the city.
Two questions worth reading before you ring anyone: what to do first when a code appears and how to tell whether it is yours to fix.
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Related: the PM checklist that prevents the most common codes outright, and the operator guides for symptom-first diagnosis.
Not sure this is the right make? The lookup by code shows every make that uses a given code, and flags the ones that mean different things depending on the machine in front of you.