Hobart LXn/LXGn - Error 004: Booster temperature not reached during wash cycle

⚠️ Caution / Monitor Closely
Warning: The information provided here is for educational purposes only. Working with commercial kitchen equipment involves high voltage, gas, and high temperatures. We strongly recommend contacting a certified service technician for any repairs. We are not responsible for any damage or injuries resulting from DIY repair attempts. This information is provided 'as is' without any guarantees of completeness or accuracy.

TLDR

On your LXn/LXGn SERIES DISHWASHERS unit, error code 004 indicates the booster temperature failed to reach its setpoint within the allocated time during the wash cycle. This issue often stems from insufficient water supply, a faulty booster heater element, a defective high-limit thermostat, or a malfunctioning temperature sensor. Prompt diagnosis and repair are crucial to ensure proper sanitization and machine operation.

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Technical Details

Repair Steps:

  1. Verify Water Supply and Pressure: Ensure the hot water supply valve to the dishwasher is fully open and that adequate water pressure is available. Low incoming water pressure can impede proper filling and heating.
  2. Check Booster Tank Fill Level: Observe the booster tank fill level. An insufficient water level will prevent the heater from operating correctly and could trigger the high-limit thermostat prematurely. Ensure the fill valve is working.
  3. Inspect Booster Heater Elements: Turn off power to the machine. Access the booster tank and use a multimeter to check the continuity of the booster heater elements. If any element shows an open circuit or incorrect resistance, it needs replacement.
  4. Test Booster High-Limit Thermostat: With power off, locate the booster high-limit thermostat. Test for continuity across its terminals. If it’s tripped (open circuit) without an actual over-temperature condition, it may be faulty and require replacement. Press the reset button if present and safe to do so.
  5. Check Booster Temperature Sensor: The booster temperature sensor (NTC probe) provides temperature feedback to the control board. With power off, test its resistance using a multimeter and compare it to the manufacturer’s temperature/resistance chart. A sensor reading outside the expected range indicates a fault.
  6. Verify Booster Heater Contactor/Relay: With power on (and extreme caution), check if the booster heater contactor or relay is engaging when the unit calls for heat. If the contactor is not pulling in, check its coil voltage and the control circuit leading to it.
  7. Inspect Wiring and Connections: Thoroughly inspect all wiring and connections related to the booster heater circuit, including those to the elements, sensors, thermostat, and contactor. Look for loose, corroded, or burnt wires that could interrupt the circuit.
  8. Reset and Monitor: After performing checks and repairs, reset the error by pressing the ENTER button (as per original description). Run a cycle and carefully monitor the booster temperature to ensure it reaches and maintains the setpoint.

Common Questions:

Q: Why is the booster temperature so critical in a commercial dishwasher?

A: The booster temperature is crucial for proper sanitization. Commercial dishwashers rely on high water temperatures (typically 180°F / 82°C or higher) during the final rinse cycle to kill bacteria and meet health code standards. Without this temperature, dishes are not adequately sanitized, posing a health risk.

Q: Can I continue using my HOBART LXn/LXGn dishwasher if error 004 persists?

A: It is strongly advised not to continue using the dishwasher if error 004 persists. Operating without the proper booster temperature means your dishes are not being sanitized effectively, which can lead to health code violations and potential foodborne illnesses. The machine requires professional service.

Q: What does “setpoint not met within predetermined time” specifically mean for the booster?

A: This means the dishwasher’s control system activated the booster heater and expected it to reach a specific sanitizing temperature (the setpoint) within a certain timeframe. If the temperature doesn’t rise to the setpoint within that allotted time, the machine triggers error 004, indicating a heating failure.

When to call a technician

Consider calling a certified technician if:

  • The error keeps coming back after you've tried the steps above.
  • You're not comfortable doing the checks or repairs yourself.
  • You notice unusual noise, smell, or behaviour.
  • Equipment is under warranty and you want official service.
  • You need the unit back in service quickly with minimal downtime.

Need Professional Help?

Our certified technicians can help you on-site.

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