Bosch Dishwasher Error Code F51

F51 indicates a heater pressure switch fault. During the initial drain phase, the control board activates the heater relay and checks for closed contacts at points 21/22 or 11/12 on the heater pressure switch. If those contacts are not detected as closed, the board triggers F51 and stops the cycle. The fault typically points to a failed heater relay, a wiring problem, or a defective pressure switch.

No, you should not continue running the dishwasher while F51 is active. The error indicates that the heating system safety monitoring circuit is not functioning correctly. Running the appliance in this condition could allow the heater to operate without proper oversight, which creates a risk of overheating or damage to internal components.

Resetting the dishwasher may temporarily clear the F51 code, but the fault will return if the underlying cause has not been repaired. A reset does not fix a failed relay, a broken wire, or a defective pressure switch. It is best to diagnose and correct the root cause before attempting to resume normal use.

Some causes of F51 are DIY-friendly, particularly checking and reseating plug connections or testing wires for continuity with a multimeter. Replacing a heater relay is also manageable for someone comfortable working with appliance wiring. However, if the fault involves the heater pressure switch or control board, accurate diagnosis requires component-level testing, and incorrect repairs could create safety issues.

Repair costs vary depending on the root cause. If the issue is simply loose or corroded connections, the fix may cost nothing beyond your time. Replacing a heater relay typically runs in the range of $20 to $80 for the part, while a heater pressure switch can range from $30 to $100. If a service technician is needed, labor costs will add to those figures.