Manitowoc E20 Error Code

What does Manitowoc E20 mean?

E20 signals a water system fault — the control detected an abnormal water level or flow condition during fill, circulation, or drain operations. The fault triggers when the high water probe activates without the low water probe being active first, or when evaporator temperature readings indicate water is not circulating correctly. The machine shuts down to prevent damage from a flooded or dry water system.

Symptoms

• Machine shuts down with E20 (WTR Fault) on the display.
• Water reservoir does not fill or overflows during operation.
• Water pump runs but ice slab does not wet evenly, indicating low water flow.
• Drain cycle does not complete, leaving standing water in the sump.

Common causes

• Clogged water inlet valve restricting fill flow or not opening fully.
• Water pump failure preventing circulation over the evaporator.
• Plugged pump filter or sump screen blocking water flow.
• Faulty water level probe (high or low) giving incorrect water level signals.
• Drain pump failure or kinked drain hose preventing sump drainage.

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Diagnostic steps

1. Check incoming water supply

   Verify the water supply valve is fully open and supply pressure is between 20 and 80 PSI. Low pressure prevents the fill valve from delivering adequate flow within the allotted fill time.

2. Inspect and clean the water inlet valve

   Remove the inlet valve screen and rinse it under running water. A partially blocked screen reduces fill rate and triggers E20. Replace the valve if the screen is undamaged but flow remains restricted.

3. Inspect the water pump and sump filter

   Remove and clean the sump filter screen. Confirm the water pump runs during the freeze cycle and circulates water visibly over the evaporator. A pump that hums without moving water needs replacement.

4. Inspect water level probes for mineral buildup

   Clean the high and low water probes with a soft cloth and Manitowoc cleaner. Heavy mineral scale on the probe rods causes false level readings. Replace probes that are corroded or physically damaged.

5. Check drain pump and drain hose routing

   Confirm the drain hose has no kinks and terminates at the correct height per the installation manual. Test drain pump operation separately if the sump fails to drain during the drain cycle.

When to call a professional

If water pump or drain pump replacement does not resolve E20, and water level probe replacement also fails to clear the fault, the control board water probe input circuit may be faulty. Control board diagnostics require a factory-trained technician.