I have an ft900 with steam booster . The final rinse temp shoots right up over 212 then x's out. I changed the tank heat thermostat like Hobart said still doing same thing

Error P3, Rinse Tank Booster Thermister is faulty

SOLVED: Hobart LXI Dishwasher a P3 code is flashing ...

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Mar. 11, 2010 - It is monitoring the rinse temp. P2 is the booser probe, and P1 is the wash tank. The control board will store error codes, so once changed, you ... 1 answer · 11 votes: The p3error is an open or shorted booster thermistor.take off btm panel on the right side is the bstr, do when cold and no power to mach.,TURN OFF BREAKER, ...
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18H doesn't exist

https://www.google.com/search?q=hobart+lx18c+18H+error+code

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Probe Error FnlRns - (Ensure that the supply water valve to the final rinse booster is open.)
https://my.hobartcorp.com/resourcecenter/ProductDocumentation/F44126.pdf

For a machine without a break-tank (a.k.a. cistern) and booster pump: check the inline debris strainer on the rinse water pipework; check you're not missing any rinse jets; check the inlet valve is fully opening.

For a boosted machine, check the pump impeller isn't disintegrating; check that the flexible hoses to the booster pump aren't collapsing internally.

For both machines: descale if you're in a hard water area.

your right dont guess the board is bad!

Probably a bad booster tank termperature probe (thermistor). This is threaded into the booster heater and has two small black wires entering it.

The following procedure will result in a some water coming out of the booster heater. Allow the booster heater to completely cool, and shut off the circuit breaker for the dishwasher before proceding.

Prepare a new temp. probe with teflon tape, then unscrew the old probe from the booster heater and quickly install the new probe. Assuming the heater is cooled, you can hold your finger over the hole vacated by the old probe to prevent excessive water from pouring out of the booster heater.

All Hobart dishwashers will have a wash tank heating element, but the rinse water is not heated by the dishwasher, unless it has a built-in booster heater. Usually a separate booster heater is used to heat rinse water to 180-190 deg. F for hot water sanitation.

make sure all the curtains are there ,also check for any baffles missing from mach. should be 2 1 on incoming side 1 on outgoing, also ck hood vents had problem before with vents wide open sucking heat right out of warewasher

3 Con, is the booster heat contactor. If it is chattering, the fault will be in the booster. There are a few different boosters in the AM14. can you post the ML number from the data plate, or describe if the booster is a square Hatco HCM-10, or a round stainless booster with a 13 kw multi wired element.. All boosters use a low water cut off circuit, a high limit thermostat and a control thermostat. The old Hatcobooster uses mechanicqal components, where the new rount tank uses probes and a control board. The board has 3 leds. red is calling for heat, yellow is open thermistor, and green is shorted thermistor.
AM14's had a variety of different control circuit voltages, ranging from 240/208/120 and 24 volt AC. Check the transformer secondary for correct output to controls, trace through circuit until voltage pulses. If new style, it could be just scaled up probes not reading water. Drain the tank with the power off before removing probes.

bad thermostat or contactor

145 degree is just your hot water temp and that your dishwasher hot water booster is not working assuming that this machine has worked in the past to produce final rinse water above 180 degrees. Remove the bottom panel and to the right you will see the booster tank, look for a nickel size component with a small red button on it. Try pushing on it to reset it. If that does not work, check for voltage at your heating element on your booster tank. (the thicker wires) If voltage is present then your heating elements need replacing.