Bosch Dishwasher Error Code E18 — Water Intake Restricted

What Does This Error Mean?

E18 means your Bosch dishwasher is trying to fill with water but can't get water in fast enough. The machine expects a certain volume of water within a specific time window. If that window expires without enough water, E18 triggers and the cycle stops. This is almost always a water supply issue — not an internal dishwasher fault. Check your water supply valve and inlet hose before assuming anything inside the machine is broken.

Affected Models

SMS46GI01A
SMS68MI02G
SMV68IX00E
SPV6ZMX23E
SMS8YCI01E
Most Bosch Series 2, 4, 6, and 8 dishwashers

Common Causes

Water supply shut-off valve under the sink is partially closed, restricting flow
Kinked or crushed water inlet hose behind the dishwasher limiting water flow
Clogged mesh filter screen at the inlet valve — debris from supply pipes blocking flow
Low household water pressure below the minimum required (20 PSI)
Clogged or faulty water inlet valve restricting flow despite adequate supply pressure

How to Fix It

Check the water supply valve under the kitchen sink. It should be fully open (turned all the way counter-clockwise). A valve that's even slightly restricted can cause E18. Fully open the valve and run a test cycle.

Shut-off valves that haven't been turned in a long time can develop scale buildup that prevents them from opening completely. If the valve feels stiff or gritty, it may need replacement.
Inspect the water inlet hose at the back of the dishwasher. Make sure it isn't kinked, bent sharply, or pinched against the side of the cabinet. Pull the dishwasher forward slightly to check the hose behind the unit.

Hoses often get kinked when the dishwasher is pushed back into the cabinet after repairs or cleaning. A kinked hose can look fine from outside but be collapsed internally.
Clean the inlet filter screen. Turn off the water supply, disconnect the inlet hose from the valve at the back of the dishwasher, and look inside the valve's inlet port. You'll see a small mesh screen. Remove it carefully and clean it under running water. Replace it and reconnect the hose.

Rust particles and sand from aging supply pipes are common causes of a clogged inlet screen. This is a free fix if that's all it is.
Test your water pressure if you suspect low supply pressure. A garden hose pressure gauge (under $15 at hardware stores) screwed onto any outdoor bib will give you a reading. Bosch requires 0.05-1.0 MPa (about 7-145 PSI) at the inlet. Below 7 PSI, the inlet valve won't open properly.

If pressure tests show consistently low flow, contact your water supplier or check your home's pressure reducing valve.
If supply is good and the screen is clean but E18 persists, the inlet valve solenoid may be failing. The solenoid controls how wide the valve opens — a partially failed solenoid only opens partway, restricting flow. Replace the inlet valve with a Bosch-specific part for your model number.

When replacing the inlet valve, also inspect the AquaStop hose connection if your model has one — AquaStop restriction can contribute to E18.

When to Call a Professional

If the supply valve and hose check out clean, the inlet valve itself may need replacement. A Bosch inlet valve typically costs $30-$65 for the part. This is often a manageable DIY repair. A technician charges $130-$260 for the full repair including parts and labor.

Frequently Asked Questions

How is E18 different from E16 on a Bosch dishwasher?

E16 means water is coming in when it shouldn't — an unexpected fill event. E18 means water isn't coming in fast enough during a normal fill phase — a restricted flow problem. They're opposite problems. E16 usually points to a stuck-open valve. E18 usually points to a restricted supply or partially closed/clogged valve.

E18 appeared right after I had plumbing work done. Is that related?

Almost certainly yes. Plumbing work often disturbs loose scale and debris in pipes, sending it into the supply lines. That debris can clog the mesh filter screen at the dishwasher inlet valve. Always clean the inlet filter screen after any plumbing work near the kitchen water supply.

Could a water softener cause E18?

It can if the softener's service cycle is running at the same time as the dishwasher. Water softeners can dramatically reduce pressure and flow rate during their regeneration process. Try running the dishwasher at a different time of day to see if E18 goes away. You can also schedule the softener's service cycle for late at night when appliances aren't in use.