What F40 Means
WHICH MACHINE THIS APPLIES TO: the Asko professional dishwasher DWC6432, in its DWC6432BIXXLSU and DWC6432BIXXLS forms, together with the DWC6433BIXXLS, whose manual prints the identical thirteen-code table. Three separate Asko documents carry that table and they agree with each other character for character. It belongs to Asko's professional line and it is grouped here with the rest of that line.
WHY A DOMESTIC ASKO DISHWASHER PAGE IS THE WRONG PAGE FOR THIS MACHINE: most of these numbers exist on the domestic machines too, and several of them carry different instructions there. The plainest example is the water pressure specification - the professional manual requires between 15 and 140 psi, which is 0.1 to 1.0 MPa, and the domestic books print a different and much lower minimum. The professional machine also has three codes that no domestic Asko dishwasher has, and it does not have one that several domestic machines do. Read the professional table for a professional machine.
WHAT F40 MEANS ON THIS MACHINE: the error table gives the message as "Inlet valve leakage", and the action is to turn off the water supply valve and call service.
WHAT THE MACHINE HAS WORKED OUT: that water is getting past the inlet valve when the valve should be closed. The valve is what stands between the mains supply and the inside of the machine at every moment the appliance is not filling, which is most of the day and all of the night. A valve that passes water is a machine that keeps taking water in with nothing running.
WHY THIS IS THE CODE ON THE PROFESSIONAL MACHINE LEAST WORTH ARGUING WITH: because the instruction is to close the supply and call, and because the risk it describes does not stop when the machine is switched off. Power does nothing to a valve that is leaking; only the supply valve does. In a commercial kitchen that closes overnight, this is the fault that fills a floor while nobody is there.
WHAT ASKO DOES NOT ASK YOU TO DO: anything else. There is no check, no filter to clean and no retry in the published action. That is unusual on this table, where most codes come with something to look at, and the absence is the point.
CLASSIFICATION: fault with a continuing water-escape risk while the supply is open.
Common Causes of F40
- Inlet valve failing to close fully
- Debris or scale holding the valve seat open
- Valve body or its seal damaged
- Control unit energising the valve when it should not
- Water detected in the base, which is what brings the fault to the machine's attention
🔧 One Safe Check You Can Try
Turn the machine's water supply valve off. Do it now, before anything else, and leave it closed until the machine has been repaired - that is the manufacturer's first instruction and it is the only action that stops the fault continuing. Then take the machine out of service so nobody starts a programme on it, and in a kitchen that means telling the team as well as switching it off. Look at the floor in front of and beneath the appliance and at the units either side, and at the cabinet base if anything is visible, because a valve that has been passing for a while may already have put water somewhere. If water is present, keep people and trolleys away from it until it is cleared, since a wet floor in a working kitchen is a hazard in its own right. Then call. Do not run a cycle to see whether the fault repeats, do not switch the machine off and on hoping it clears, and do not draw the appliance out to look behind it - the valve is at the back of a built-in machine with the supply connected to it, and the whole point of the instruction is that the supply comes off first.
⚠ Why You Shouldn't Go Further Than That
- Closing the water supply valve is the manufacturer's first instruction, and it is the only action that stops water entering while the fault exists.
- Switching the machine off does not stop a leaking valve, because the valve is held closed mechanically and not by the control.
- The valve sits at the back of a built-in machine with the supply connected, so reaching it means unfastening the appliance and drawing it out with live plumbing attached.
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.