Your washing machine has stopped mid-cycle, fills but never starts washing, or refuses to spin. Before you blame the motor or the control board, consider the sensors — small parts that track the water level, the door, the temperature and the load. When one sends the wrong signal, the machine stops.
Each sensor fails in its own recognisable way, and several checks are simple enough to do yourself.
First: Make It Safe Before You Touch Anything
Before you inspect anything, unplug the machine and turn off the water taps behind it. Wait for the drum to stop and never force a locked door open. Looking, cleaning and checking hoses are fine; opening the cabinet to test live parts is a job for a qualified technician.
The 5 Sensors Inside Your Washing Machine
Most machines use the same five sensing jobs, and the symptoms of failure are much the same.
1. Water-level sensor (pressure switch)
The sensor that fails most often. A thin tube runs from the outer tub to a pressure switch at the top; as water fills the tub, air in the tube is compressed and the switch tells the control board the level is right. When the tube clogs with detergent residue or splits, the machine keeps filling and never starts washing.
2. Door or lid sensor (door lock)
The door lock confirms the door is fully closed and locks it before the drum spins. If it fails, the machine will not start, or it fills and then refuses to agitate or spin. Clues include a door-lock error code, a lock that clicks repeatedly, or a door that will not unlock. On top-loaders the lid switch fails the same way.
3. Temperature sensor (thermistor)
A small sensor on the heating element or tub measures the water temperature so the machine can heat to your chosen setting. When it fails, the machine may wash only in cold water, overheat the water, or stop with a heating error. A tell-tale sign is clothes coming out cold on a 40-degree cycle.
4. Load and imbalance sensor
Modern machines weigh the load at the start of the cycle — often using the motor itself — and set the water level and wash time accordingly. During spin, an imbalance sensor watches for a badly shaking drum. When it goes wrong, the machine may refuse to spin or keep redistributing the load. A single heavy item, such as a soaked towel, can trigger the same behaviour, so rule out an unbalanced load first.
5. Drain and water-flow sensor
Some machines also monitor filling and draining directly: a flow sensor at the inlet checks water is arriving, and the control board watches how long draining takes. If the machine fills slowly or sits full of undrained water, the fault may be a sensor — but a kinked hose, blocked filter or faulty inlet valve is just as likely.
How to Tell Which Sensor Has Failed
- Fills forever, never starts washing: water-level sensor or its pressure hose.
- Fills, then sits silent: water-level sensor or door/lid lock.
- Will not start, or the door will not lock: door or lid sensor.
- Washes only in cold water, or the cycle drags on: temperature sensor or heating element.
- Will not spin, or spins slowly and keeps stopping: load or imbalance sensing — first check the load is balanced.
- Stops with an error code: look it up in your model’s manual.
If your machine has stopped working altogether, start with our guide to a washing machine not working. If water is escaping too, see water leaking from under your washing machine.
Safe DIY Checks You Can Try
Work through these in order, with the machine unplugged and the water off.
1. Reset the machine
Unplug it for five to ten minutes, then plug it back in and try a short cycle. Many sensor errors are one-off glitches a reset clears; if the fault comes straight back, it is a real problem.
2. Check the water supply and hoses
Make sure both taps are fully open and the inlet hoses are not kinked behind the machine — a slow fill can look exactly like a water-level sensor fault. Clean the small mesh filters where the hoses meet the machine.
3. Clean the pressure hose
The water-level sensor’s thin tube is the most common cause of sensor trouble. With the machine unplugged, pull it off the pressure switch and check for blockages or splits. Blow gently through it — you should hear the switch click. If you hear nothing, the switch may have failed.
4. Inspect the door lock and seal
Check the rubber seal for trapped coins, lint or damage that stops the door closing fully. Push the door firmly shut and listen for the lock engaging. If it clicks repeatedly, the lock is worn and needs replacing.
5. Clean the drain pump filter
A blocked filter slows draining, which the machine can read as a drain-sensor fault. It sits behind a small panel near the base — put a towel down, unscrew it slowly, and clear out lint and coins.
6. Check the load and the levelling
Run a spin with the drum empty. If it spins fine empty but not with a load, the imbalance sensor is doing its job — redistribute the clothes and try again. If the machine rocks, adjust the feet until it sits level.
What Not to Do
- Do not bypass a sensor. Shorting out a door lock or water-level switch removes a safety device: the drum can spin with the door open, or the machine can overfill and flood.
- Do not run the machine with a panel off, or keep resetting and re-running it. Exposed live parts are a serious hazard, and forcing cycles can burn out the pump or motor.
- Do not pour cleaner into the pressure hose, and do not guess at parts. Cleaner can damage the switch diaphragm, and sensors are rarely interchangeable across brands — order by your exact model number.
When to Call a Technician
Call a technician if the pressure switch needs replacing and you cannot reach it safely, if the door lock is buried behind the front panel, or if the control board is the problem — a board fault can mimic every sensor fault at once.
A pressure switch or door lock is usually a moderate repair: the part is inexpensive and the job is often under an hour. A control board replacement is the expensive one — on a machine over eight to ten years old, if the quote tops half the price of a comparable new one, replacing the machine is usually the better spend.
Frequently Asked Questions
How do I know if my washing machine sensor is bad?
Look at the pattern: endless filling points to the water-level sensor, no start to the door sensor, cold-only washes to the temperature sensor, and no spin to load or imbalance sensing.
Can I use my washing machine if a sensor is not working?
It is best not to. A faulty water-level sensor can overfill and flood, a faulty door lock can let the drum spin with the door open, and a faulty temperature sensor can overheat it.
How do I reset a washing machine sensor?
Unplug the machine for five to ten minutes, then plug it back in and run a short cycle. This clears one-off glitches; if the same fault returns immediately, the sensor or its wiring is genuinely faulty.
Why does my washing machine keep filling with water and never start?
The water-level sensor does not know the tub is full. The usual cause is a clogged or split pressure hose, or a worn-out switch. Clean the hose first — it is the cheapest fix.
How much does it cost to fix a washing machine sensor?
It depends on the sensor. A pressure switch or door lock is usually a moderate repair, while a control board fault is the most expensive fix and may not be worth it on an older machine.
Conclusion
A washing machine sensor not working sounds serious, but it is often one small part sending the wrong message. Start with the symptom: endless filling means the water-level sensor, no start means the door lock, cold washes mean the temperature sensor, and no spin usually means the load sensor — or an unbalanced load.
Work through the safe checks first — a reset, the hoses, the pressure tube, the door seal and the pump filter — because several cost nothing and fix the problem outright. For anything inside the machine, a technician’s diagnosis is money well spent.