What Does Error Code NO Mean on a Bosch Washing Machine?
Check that the cold water tap behind the machine is fully open, straighten any kinks in the inlet hose, and restart the cycle — this resolves the majority of NO error cases (takes about 5 minutes).
Fault description
Error code NO appears on certain basic Bosch washing machine models when the appliance fails to detect water entering the drum at the start of a cycle or during a fill phase. It is functionally equivalent to the E17 fault code used on other Bosch models, and both point to the same underlying problem: the machine is not receiving an adequate water supply.
When this error triggers, the wash cycle will pause or stop entirely, and the error code will be displayed on the control panel. The machine is protecting itself — running a drum without water could damage the motor, heating element, and drum bearings. In most cases, the fault lies outside the machine itself, making it one of the more straightforward errors a homeowner can investigate.
Before assuming a component has failed, work through the supply-side checks first. The majority of NO errors are resolved without replacing any parts at all.
Causes
- Water tap turned off or not fully open — The cold water supply tap behind the machine may have been accidentally closed or left only partially open. Even a tap that is three-quarters open can restrict flow enough to trigger the error.
- Kinked or blocked inlet hose — The rubber hose connecting the tap to the machine can become kinked if the machine has been pushed back against the wall. A partial blockage from limescale or debris inside the hose can also reduce flow to a level the machine cannot work with.
- Blocked inlet hose filter mesh — A small mesh filter sits inside the inlet hose connection at the back of the machine. Over time this filter collects sediment and limescale, gradually reducing water flow until the machine can no longer fill correctly.
- Faulty or seized water inlet valve — The inlet valve is an electrically operated solenoid valve that opens to allow water in. If the solenoid coil fails or the valve body becomes clogged with scale, it will not open fully or at all, preventing water from entering.
- Low mains water pressure — Bosch washing machines require a minimum water pressure — typically around 0.5 bar — to fill correctly. If your household pressure drops below this, perhaps due to works in the street or a shared supply, the machine may not fill in time and will display the NO error.
- Faulty pressure sensor or wiring — The pressure sensor (also called a pressure switch or level sensor) monitors how much water is in the drum. If it is faulty or its connecting hose is blocked, it may incorrectly report that the drum is already full or fail to signal that filling has begun, causing the machine to stop and display the error.
Step-by-Step Fix
- 1
Check the water supply tap
Locate the cold water tap on the wall or under the sink behind the machine and confirm it is turned fully anticlockwise (open). If it was closed or only partially open, open it fully and restart the cycle. This single check resolves the error in a significant number of cases.
- 2
Inspect the inlet hose for kinks
Pull the machine gently away from the wall and run your hand along the full length of the inlet hose. Straighten any kinks or tight bends you find. Once the hose lies in a smooth curve, push the machine back carefully to avoid re-kinking it, then restart the cycle.
- 3
Clean the inlet hose filter mesh
Turn off the water tap, then unscrew the inlet hose from the back of the machine — have a towel ready as some water will spill. Use a pair of needle-nose pliers or a small screwdriver to carefully pull out the mesh filter from the machine's inlet port. Rinse it under the tap and remove any visible debris or limescale. Refit the filter, reconnect the hose, and turn the tap back on.
- 4
Check household water pressure
Turn on a cold tap elsewhere in the house and observe the flow. If pressure seems unusually low throughout the property, contact your water supplier to check for local supply issues. You can also ask a plumber to measure pressure at the machine's supply point if you suspect a persistent low-pressure problem.
- 5
Test the inlet valve
With the machine unplugged and the water supply off, disconnect the inlet hose and inspect the valve body at the back of the machine for visible scale build-up or damage. You can test the solenoid coil with a multimeter — a reading outside the manufacturer's specified resistance range (typically 3–5 kΩ) indicates a failed coil. A faulty inlet valve will need to be replaced.
- 6
Inspect the pressure sensor and its hose
The pressure sensor is usually located inside the machine's top panel, connected to the drum by a thin rubber hose. Unplug the machine, remove the top panel (two screws at the rear), and check that the small rubber hose running to the sensor is not blocked, split, or disconnected. Blow gently through the hose to clear any blockage. If the sensor itself is suspected faulty, it will need testing or replacing.
- 7
Perform a reset
After completing any of the above checks, switch the machine off at the mains, wait 60 seconds, then switch it back on and select a fresh cycle. This clears any stored fault state and allows the machine to attempt a normal fill sequence from scratch.
Affected models
Select your model to see its full troubleshooting page.
When to call a service technician
If you have confirmed the water supply is fully open, the hose is clear and undamaged, and the filter mesh is clean, but the machine still displays the NO error, the fault is likely internal. A failed inlet valve solenoid, a defective pressure sensor, or a wiring fault between these components and the control board are not straightforward DIY repairs and carry a risk of water damage if reassembled incorrectly.
You should also contact a service technician if you notice any signs of water leaking from the inlet valve area, if the machine trips your household electrics when it attempts to fill, or if the error code returns immediately after a reset with no obvious supply-side cause.
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Frequently Asked Questions
Is error code NO the same as error code E17 on Bosch washing machines?
Yes, they describe the same fault — water not entering the machine within the expected time. The NO code appears on certain basic or older Bosch models that use a simpler display, while E17 is shown on models with a more detailed numeric fault code system. The causes and fixes are identical for both.
Can I still use my washing machine while it shows the NO error?
No. The machine will not progress past the fill stage while the error is active, so running a cycle is not possible until the fault is resolved. Attempting to force a cycle without water present could damage the heating element and drum bearings, so it is best to diagnose and fix the issue first.
How do I know if my water inlet valve needs replacing?
If the filter mesh is clean, the hose is clear, and the tap is fully open but the machine still will not fill, the inlet valve is a strong suspect. You can confirm this by testing the solenoid coil with a multimeter — a reading outside the normal resistance range, or an open circuit, means the valve has failed and needs replacing. A valve that is visibly cracked or leaking should also be replaced immediately.
My machine fills fine on some cycles but shows NO on others — what does that mean?
Intermittent filling problems often point to a partially blocked inlet valve or a filter mesh that is not fully blocked but is restricting flow enough to cause occasional failures. It can also indicate borderline low water pressure that dips below the machine's minimum requirement at certain times of day. Cleaning the filter mesh and checking pressure are the best starting points.
How often should I clean the inlet hose filter on my Bosch washing machine?
In hard water areas, cleaning the inlet filter every six months is a sensible routine. In soft water areas, once a year is usually sufficient. The process takes only a few minutes and can prevent the NO error from occurring in the first place, making it one of the most worthwhile pieces of basic washing machine maintenance.