What Wash Heater Error Means
Four flashes then two means the wash heater's current sense reading has fallen outside the expected range. Viking's FDB451 dishwasher service manual (2012, page 13) lists four causes, and unusually it includes the temperature sensor alongside the heater itself, the wiring and the main control.
Common Causes of Wash Heater Error
- Wiring between the main control and the wash heater disconnected
- Wash heater has failed
- Temperature sensor feeding the control a reading that will not let the heater run
- Main control misreading the heater's current draw
🔧 One Safe Check You Can Try
There is nothing to do from the front, but the sign is recognisable: plastics coming out wet, glassware filmed, and cycles that finish without ever feeling hot when the door is opened.
⚠ Why You Shouldn't Go Further Than That
- Viking gives the water heater a nominal 12 ohm reading between named terminals, and reaching those terminals means the machine isolated and opened.
- The heater is a flow-through element rather than a tank heater, so it depends on the wash pump moving water past it - a fact that ties this code to the flow codes as well as to the element.
- Because the temperature sensor is on the cause list, replacing the heater without checking the sensor can leave the code exactly where it was on a brand-new element.
Opening a panel to inspect or repair something yourself doesn't automatically cancel your manufacturer's warranty — but it can risk accidental damage, and some manufacturers do have specific service conditions. Check your product's warranty terms, or ask us, before deciding.