What F4 Means
WHICH MACHINES THIS APPLIES TO: single-character F4 belongs to the DW20 platform (the US 3000 and 5000 Series) and the DW70 platform. Current DBI, DFI and DSD machines show water inlet problems as F12 or F67 instead.
DW20 AND DW70 PLATFORM - WHAT F4 MEANS: the service manual reads "Water intake fault. Less than 80 pulses within 60 seconds or correct number of pulses is not achieved within 255 seconds. Programme interrupted." Asko measures the water going in with a flow sensor that sends a pulse for each small quantity that passes. The control is therefore not asking whether water arrived; it is counting how fast it arrived and how much. Fewer than 80 pulses in the first minute means almost nothing is coming through. Failing to reach the target count in four and a quarter minutes means water is arriving, but far too slowly.
WHAT THE MACHINE DOES NEXT: it stops the programme rather than running a wash with too little water. On the DW20.4 and DW20.5 text panels the same fault reads "Water Inlet Fault - Make sure the water supply is open", which is Asko's own consumer instruction and the sensible place to start.
CLASSIFICATION: fault, but one with a genuine owner check at the front of it. The two most common causes are outside the machine.
Common Causes of F4
- Supply tap to the dishwasher closed or only partly open
- Inlet hose kinked or crushed behind the cabinet
- Filter screen in the inlet hose coupling blocked with scale or grit
- Low mains water pressure, or a pressure-limiting valve restricting the supply
- Inlet valve not opening fully
- Flow sensor miscounting, or its wiring damaged
🔧 One Safe Check You Can Try
Start with the check that needs no tools and no access: confirm the dishwasher's own supply tap is fully open, and that nothing else has shut the water off - a service valve under the sink turned during other work, or a stop tap left closed after a plumbing job. Then look at the inlet hose along its whole run behind and beside the machine for a kink or a crush point where the cabinet has been pushed back. If you want to check the filter screen in the inlet hose coupling, close the supply tap first and let the pressure off before unscrewing anything, and have a towel underneath, because the hose holds water. Note that the filter screen is only an owner-accessible item on the machines where Asko documents it: the inlet-hose filter check appears in the consumer instructions for the later water inlet codes, and on the DW20 and DW70 consumer manuals the documented instruction stops at "make sure the water supply is open". Everything else on the manual's list - flow sensor, inlet valve, wiring - is inside the machine.
⚠ Why You Shouldn't Go Further Than That
- The inlet hose is under mains pressure, so the supply tap has to be closed and the pressure released before any coupling is undone.
- The inlet valve and the flow sensor are behind the base panel, and reaching them means isolating the dishwasher from power and drawing it out of the cabinet with its plumbing still 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.