What this error means
Water level fault — the dishwasher has detected an abnormally high water level
The OC or OF error means the water level sensor has detected that the water in the dishwasher base has exceeded the normal operating level. This is a safety-critical fault. The most common causes are a blocked drain preventing normal water turnover, a stuck-open inlet valve allowing water to accumulate uncontrolled, a failed water level sensor (pressure switch), or a blocked pressure hose preventing the sensor from reading correctly.
What you'll need first
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Step-by-step
Symptoms to look for
- Dishwasher fills to an unusually high level — water visible near the door seal
- OC or OF displayed during or shortly after the fill phase
- Water escaping from the door seal during a fill cycle
- Machine fills but does not proceed to wash — sits full of water with OC showing
What to check
Turn the water supply tap fully clockwise (closed) and unplug the machine. Wait 5 minutes then open the door very slowly and stand back — if the water level is at or near the door seal, water will run out as the door opens. Have towels ready. If the level is high, scoop water out with a jug before attempting anything else.
Clean the filter assembly thoroughly — remove both the cylindrical coarse filter and the flat fine mesh filter and scrub them clean. A blocked filter prevents water from draining between fill phases, allowing the level to accumulate to the point of triggering OC. Refit the filter, plug in briefly and run a Drain programme to empty the tub.
With the dishwasher unplugged, remove the lower kickplate panel. Locate the narrow pressure hose running from the base of the tub to the water level pressure switch (a small cylindrical sensor with an electrical connector and the hose on its lower port). Disconnect the hose from both ends and blow through it to confirm it is completely clear. Check the drum connection stub for limescale or debris.
With the machine unplugged and the water supply turned off, inspect the inlet valve body (accessible behind the kickplate panel). If the valve plunger has stuck open, water will continue entering whenever the tap is on — even when the machine is powered off. Check whether water drips from the spray arm or into the tub with the machine unplugged and the tap open. If it does, the valve has stuck open and must be replaced.
With the kickplate removed, shine a torch into the machine base. Look for signs of standing water around the pump, the tub base, and in the base tray. If water is present in the base tray the level sensor float may have been triggered. Dry the base tray with cloths and allow 2 hours to air dry before testing.
Once the tub is drained, the filter is clean, and the inlet valve has been confirmed to close correctly, restore power and water supply and run a Quick Wash while remaining present. Confirm the water level stabilises at the normal operating level — well below the door seal.
When to call an engineer
- Inlet valve plunger is stuck open — water enters even when machine is unplugged and tap is on
- Pressure hose confirmed clear but overfilling persists — pressure switch has failed
- Water present in base tray with no identifiable external leak — tub or pump seal is weeping
- Control board relay stuck in closed position — continuously energising the inlet valve
Frequently asked questions
Is OC dangerous?
Can a blocked filter cause OC?
How do I safely open the door after an OC fault?
What is the difference between OC and LC on a Samsung dishwasher?
🎯 What is likely causing this fault?
⚠️ Estimates based on common faults — not a guaranteed diagnosis. Always verify before ordering parts.
Parts you may need
Enter your model number to filter results to your exact machine
Usually found on a label inside the door frame or on the back panel of the machine.
| Part | Approx. UK Cost | Find it |
|---|---|---|
| Water Inlet Valve | £10 - £20 | 🛒 Amazon UK → |
| Water Inlet Valve | £10 - £20 | 🏷️ eBay UK → |
| Water pressure switch | £20 - £30 | 🛒 Amazon UK → |
| Water pressure switch | £20 - £30 | 🏷️ eBay UK → |
ℹ️ Prices are approximate. Always check the part number matches your model before ordering. Not sure of your model number? Find out how to locate it here.