Circulation Pump Blocked / Overloaded
The F78 error code means the circulation pump in your Miele dishwasher is running but drawing excessive current or not reaching the correct speed. Unlike F51 (pump not starting), F78 indicates the pump is trying to work but is obstructed or overloaded.
~45%
DIY Fixable
$200-450
Typical Repair Cost
30 min – 2 hrs
Pro Repair Time
Quick Assessment
Answer to continue safely
Is it safe to keep using?
No. A pump running under excessive load can overheat and burn out. Continuing to use the dishwasher with F78 risks permanent motor damage and a much more expensive repair.
Can I reset the code?
Yes. Yes — turn off at mains for 5 minutes. If cleaning the filters, sump, and spray arms resolved the blockage, the code should not return.
When to stop immediately?
Stop if you notice: The pump makes a grinding or screeching sound, F78 returns after thorough cleaning of all components.
Symptoms You May Notice
Weak or no water spray
The spray arms rotate slowly or not at all, even though you can hear the pump running
Pump sounds strained
A louder-than-normal hum or whine from the pump motor during the wash phase
Cycle takes much longer
The dishwasher extends the wash phase as it struggles to circulate water effectively
F78 appears mid-cycle
The code triggers after the pump has been running for some time, as the overload condition builds
Possible Causes
Partially Blocked Impeller
A small object (glass fragment, food particle, label) is caught in the impeller — not enough to stop it, but enough to slow it.
DIY PossibleClogged Spray Arms
Mineral deposits or food particles have blocked multiple spray arm nozzles, increasing back-pressure on the pump.
DIY PossibleWorn Pump Bearings
The pump shaft bearings are worn, creating extra friction. The motor compensates by drawing more current.
Requires ProfessionalGrease Buildup in the Sump
Accumulated grease coats the sump and impeller area, restricting water flow and increasing pump load.
DIY PossibleFailing Pump Motor Windings
The motor windings are partially shorted, causing high current draw even under normal load.
Requires ProfessionalSafe Checks You Can Do
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1
Clean the Filters and Sump
Remove all filters. Clean the sump area thoroughly — remove any debris, grease, or small objects.
Use a sponge with hot water and dish soap to degrease the sump cavity.
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2
Clean the Spray Arms
Remove both spray arms (they clip or unscrew off). Run water through each arm and clear blocked nozzles with a toothpick.
Hold each arm up to light — you should see through every nozzle hole.
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3
Check for Impeller Debris
With the filters removed, look into the sump opening. Try to rotate the impeller gently. It should spin freely without resistance.
A wooden skewer works well to dislodge small objects wedged near the impeller.
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4
Run a Hot Empty Cycle with Degreaser
Run the hottest cycle empty with a dishwasher-safe degreaser or two cups of white vinegar. This helps dissolve grease buildup throughout the system.
Follow with a descaling cycle if you are in a hard-water area.
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5
Power Reset and Test
Turn off at mains for 5 minutes. Run a normal cycle and listen to the pump — it should sound smooth, not strained.
If the pump sound improves after cleaning but F78 still appears, the motor bearings may be worn.
When to Call a Professional
Contact a qualified Miele technician if:
- F78 persists after cleaning all filters, spray arms, and sump
- The pump motor sounds strained even with nothing blocking it
- The pump draws excessive current (technician measurement)
- Pump bearings are audibly worn (rattling or screeching)
- The machine is under warranty
Need Professional Help?
Find qualified Miele technicians in your area for proper diagnostics and repair.
Schedule Appointment