What Does Error Code E28 Mean on a Bosch Washing Machine?
Clean the inlet filter screens on the back of the machine by unscrewing the hot and cold water hoses, removing the mesh filters, rinsing them under a tap, and refitting them — this resolves the majority of E28 flow sensor errors by restoring proper water flow (takes about 10 minutes).
Fault description
Error code E28 points to a problem with the flow sensor — a small component that monitors how much water is entering the drum. When the machine's control board receives a reading that doesn't match what it expects, either too little water, too much, or an erratic signal, it stops the cycle and displays E28 to prevent damage or a poor wash result.
When this error appears, the machine will typically pause mid-fill or refuse to start a cycle at all. You may notice the drum stays empty or fills very slowly before the error triggers. In some cases the machine will attempt to fill several times before locking out completely.
The good news is that E28 is often caused by a simple blockage or a loose connection rather than a failed component, so there is a reasonable chance you can resolve it without calling anyone out.
Causes
- Blocked inlet filter screens — Mesh filters sit inside the water inlet connections at the back of the machine and catch debris from the supply pipes. Over time they become clogged with limescale or sediment, restricting flow enough to trigger E28.
- Kinked or partially closed water supply hose — If the machine has been pushed back against a wall, the inlet hose can become kinked, reducing water pressure to the point where the flow sensor registers an error. A tap that has been accidentally turned to a partially closed position produces the same result.
- Faulty or dirty flow sensor — The flow sensor itself contains a small paddle or turbine that spins as water passes through it. Limescale build-up or debris can jam the paddle, causing it to send an incorrect signal to the control board even when water supply is adequate.
- Faulty water inlet valve — The inlet valve controls the flow of water into the machine and is operated electrically. If one of its solenoids fails or the valve becomes partially blocked, water flow will be inconsistent and the flow sensor will report an error.
- Wiring or connector fault between flow sensor and control board — The wiring harness connecting the flow sensor to the main control board can suffer from loose connectors, corrosion, or chafed insulation. A poor connection causes intermittent or absent signals that the board interprets as a flow error.
- Failed main control board — In a small number of cases the control board itself misreads or fails to process the signal from a perfectly functional flow sensor. This is the least common cause and is usually only confirmed after all other components have been checked.
Step-by-Step Fix
- 1
Check the water supply tap and hose
Locate the cold water tap behind or beside the machine and confirm it is fully open. Pull the machine forward slightly and inspect the inlet hose along its full length for kinks or sharp bends. Straighten any kinks and push the machine back carefully so the hose is not compressed against the wall.
- 2
Clean the inlet filter screens
Turn off the water supply tap and place a towel under the hose connection at the back of the machine. Unscrew the hose, pull out the small mesh filter with a pair of pliers or a flat-head screwdriver, and rinse it under a running tap. Use an old toothbrush to remove any stubborn limescale before refitting. Reconnect the hose, turn the tap back on, and run a short cycle to see if the error clears.
- 3
Power cycle the machine
Switch the machine off at the mains socket and leave it unplugged for at least two minutes. This allows the control board to fully reset and clear any temporary fault memory. Plug back in, select a cycle, and observe whether E28 returns.
- 4
Inspect and clean the flow sensor
The flow sensor is typically located on the water inlet assembly inside the machine. Unplug the appliance, remove the back panel (usually held by two or three screws), and locate the sensor on the inlet pipe. Disconnect it, check for visible debris or limescale around the paddle, and rinse gently with clean water. Refit and test.
- 5
Check the wiring connections to the flow sensor
With the machine still unplugged and the back panel removed, trace the wiring from the flow sensor to the main harness. Press each connector firmly to ensure it is fully seated. Look for any signs of corrosion, burn marks, or damaged insulation. A corroded connector can sometimes be cleaned with electrical contact cleaner spray.
- 6
Test the water inlet valve
The inlet valve is the component the water hose connects to at the back of the machine. With the machine unplugged, check that the valve body is not cracked and that its internal filter is clear. If you have a multimeter, you can test the solenoid coils for continuity — a reading of open circuit (OL) indicates a failed solenoid and the valve will need replacing.
- 7
Replace the flow sensor
If all the above steps have been completed and E28 persists, the flow sensor itself is the most likely remaining cause. Replacement sensors are available as genuine Bosch parts or compatible alternatives. Note the sensor's position and connector orientation before removing the old one, fit the new sensor, refit the panel, and run a full cycle to confirm the fault is resolved.
Affected models
Select your model to see its full troubleshooting page.
When to call a service technician
If you have cleaned the inlet filters, confirmed the water supply is fully open, checked all visible wiring connections, and replaced the flow sensor, but the E28 error continues to appear, the fault is likely inside the main control board or in a section of wiring that is not accessible without specialist tools. At this point further DIY work carries a real risk of causing additional damage.
You should also contact a service technician immediately if you notice any signs of water leaking from the inlet valve area, burning smells, or scorch marks near any electrical components. These symptoms indicate a fault that needs professional assessment before the machine is used again.
Spare parts and service
Visit our partners for spare parts and service
Spare parts
Book a repair
Frequently Asked Questions
Can I still use my Bosch washing machine while it shows E28?
No. When E28 is active the machine has detected a problem with water flow and will not complete a cycle safely. Running it repeatedly in this state can cause the drum to run dry or the heating element to overheat. Resolve the fault before using the machine again.
How do I reset error code E28 on a Bosch washing machine?
Turn the programme dial to the off position, switch off at the mains socket, and leave the machine unplugged for two minutes. This clears the error from the board's memory. However, if the underlying fault has not been fixed, E28 will return as soon as the machine tries to fill with water again.
Is E28 the same as a water pressure problem?
They are related but not identical. Low water pressure can trigger E28 because the flow sensor detects insufficient flow, but the error can also appear when pressure is fine and the sensor or inlet valve is at fault. Check your household water pressure at another tap first — if it seems normal, focus on the machine's own components.
How much does it cost to replace a Bosch washing machine flow sensor?
A replacement flow sensor for a Bosch washing machine typically costs between £15 and £40 for the part, depending on the model. If you fit it yourself the total cost is just the part. A service technician call-out will add a labour charge on top, so it is worth attempting the replacement yourself if you are comfortable doing so.
Could hard water cause the E28 error to keep coming back?
Yes. In hard water areas, limescale accumulates on the flow sensor's internal paddle and on the inlet filter screens more quickly than in soft water areas. If E28 recurs every few months, fitting an inline water softener or using a monthly descaling tablet in a maintenance wash cycle will significantly reduce the build-up and extend the life of the sensor.