Bosch Dishwasher Check Water Light – How To Fix It

If your Bosch dishwasher is displaying a solid or flashing tap symbol, it means water is either failing to enter the machine or failing to drain away. Before you pay a £90 call-out fee for an appliance engineer, you can usually solve this yourself in under 10 minutes. In my 20 years on the tools, the issue is almost always a fatberg in the under-sink U-bend spigot, a jammed pump impeller, or an E15 anti-flood trip. Here is how to diagnose and clear the fault safely.

Decoding the Bosch check water lights

Bosch dishwashers are fitted with a self-diagnosis system to warn you of internal blockages or leaks. The tap symbol is the most common indicator. A solid tap light usually means a water inlet issue, whereas a flashing tap light points to a drainage blockage. If you see an E15 error code, the machine has detected water in the hidden base tray and triggered the anti-flood switch.

Bosch Dishwasher Fault Decoder

How to clear the Bosch E15 error (the 45-degree trick)

The E15 error means the anti-flooding sensor at the very bottom of the dishwasher has been activated. This shuts off the water supply to prevent your kitchen floor from flooding. A simple tilt is often enough to drain the trapped water and reset the float switch.

1. Unplug the dishwasher from the mains power.
2. Pull the unit out from under your kitchen worktop.
3. Place a few old towels behind the machine.
4. Carefully tilt the dishwasher backward at a 45-degree angle.
5. Hold it there until water stops running out of the base.

Once dry, push it back and turn it on. If the error returns immediately, you have an active internal leak and will need to find a good local plumber.

Checking the under-sink spigot (the most common UK drainage fault)

I constantly see drainage faults that are not actually inside the dishwasher at all. In UK kitchens, the dishwasher waste hose usually connects to a spigot on the sink’s U-bend. This is a prime location for blockages.

1. Place a bucket under your sink plumbing.
2. Loosen the metal jubilee clip holding the grey dishwasher waste hose to the spigot.
3. Pull the hose off and check inside the spigot nozzle.

You will likely find a build-up of congealed fat and food debris blocking the entrance. Use a wire brush to clear it out. Also, if this is a newly installed kitchen, check that the plastic blanking plug inside the new spigot was actually removed before the hose was attached. Plumbers forget this constantly. If the spigot is clear, you might be dealing with a larger plumbing issue and need my 5 DIY tips on unblocking a drain.

How to unjam the Bosch drain pump impeller

If your filters are clean and the U-bend is clear, your drain pump impeller is likely jammed. I usually find broken glass, un-popped popcorn kernels, or bits of hard plastic stuck in here. Because Bosch, Neff, and Siemens use the exact same internal components, this fix works perfectly if you have a Neff dishwasher not draining too.

1. Remove the bottom basket and twist out the cylindrical filter.
2. Bail out any standing water using a sponge and a bucket.
3. Locate the white plastic pump cover on the left side of the sump. You will need to pry this off. Some modern Bosch models require a T20 Torx screwdriver to remove a single securing screw first.
4. Once the cover is off, carefully feel for the white propeller blades. Using protective gloves, pull out any debris and ensure the impeller spins freely.
5. Click the cover back into place until you hear it snap.

Checking the cold water isolating valve

If you have a solid tap light, your dishwasher is not filling with water. The machine cannot wash if it cannot draw water. First, check the grey inlet hose at the back of the machine to ensure it is not kinked or squashed against the wall.

Next, find the cold water isolating valve under your sink. This connects the dishwasher to your mains water supply. Ensure the small blue or red lever is turned in line with the pipe, meaning it is fully open. If the valve is open and the hose is straight but water still will not enter, the inlet valve on the machine has likely failed. You can order a replacement inlet valve directly from eSpares and swap it out yourself.

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