What Does Error Code E20 Mean on a Siemens Washing Machine?
Perform a hard reset by switching the machine off at the wall socket, waiting 10 minutes, then powering it back on and restarting the cycle — this clears temporary control board errors in the majority of E20 cases (takes about 5 minutes).
Fault description
Error code E20 signals that your Siemens washing machine has detected heating activity at a point in the cycle when no heating should be occurring, or that the control board has lost confidence in the heating system's behaviour. The machine's electronic controller continuously monitors water temperature throughout a wash programme, and when readings fall outside expected parameters, it triggers E20 and halts the cycle to prevent damage.
When this error appears, the drum will typically stop mid-cycle and the machine may lock the door until the fault is cleared. In some cases the display will flash E20 repeatedly, while on other models a combination of indicator lights will illuminate. The fault can be intermittent — appearing once and then not returning — or persistent, which points to a more serious underlying component failure.
The heating system on a washing machine involves several components working together: the heating element, the NTC temperature sensor, the wiring between them, and the control board itself. E20 can originate from any one of these, so a methodical approach to diagnosis will save time.
Causes
- Temporary control board glitch — The control board can occasionally misread sensor data due to a brief voltage fluctuation or software state error. This is the most common cause of a single, non-recurring E20 and is usually resolved by a full power reset.
- Faulty NTC temperature sensor — The NTC sensor monitors water temperature and feeds readings back to the control board. If the sensor has drifted out of calibration, developed a short circuit, or failed entirely, the board receives implausible temperature data and raises E20.
- Heating element fault — A heating element that is partially failed or has developed a partial short can activate at the wrong time or produce erratic resistance readings. This causes the control board to detect unexpected heating and stop the programme.
- Wiring or connector damage — Loose, corroded, or damaged wiring between the heating element, NTC sensor, and control board can cause intermittent signal errors that mimic a component failure. Vibration over time is a common cause of connector loosening.
- Control board failure — If the control board's relay responsible for switching the heater circuit has stuck in the closed position, the element may receive power when it should not. This is a less common but definitive cause of persistent E20 errors that do not respond to other fixes.
Step-by-Step Fix
- 1
Hard reset the machine
Turn the machine off using the power button, then switch it off at the wall socket. Leave it unplugged for a full 10 minutes to allow the control board's capacitors to fully discharge. Plug back in, power on, and select a short wash cycle to see if E20 returns.
- 2
Check the programme selection
Confirm you are not running a programme that conflicts with the machine's settings — for example, a cold wash selected alongside a temperature setting. Turn the dial fully to the off position, then reselect your programme from scratch to rule out a dial or selector error.
- 3
Inspect the wiring and connectors at the heating element
Disconnect the machine from the mains before doing this. Remove the rear panel (usually held by two or three screws) to access the heating element terminals at the bottom of the drum. Check that both spade connectors are firmly seated and show no signs of burning, corrosion, or melting. Reseat any loose connectors firmly by hand.
- 4
Test the NTC temperature sensor
With the rear panel still removed, locate the NTC sensor — it is typically clipped into the heating element or mounted nearby on the drum casing. Disconnect it and use a multimeter set to resistance (Ohms) to test across its two terminals. At room temperature, a healthy NTC sensor typically reads between 10,000 and 20,000 Ohms; consult your model's service data if available. A reading of zero or infinite resistance indicates a failed sensor that needs replacing.
- 5
Test the heating element
With the machine still unplugged, disconnect the wiring from the heating element terminals and test resistance across them with a multimeter. A working element typically reads between 20 and 50 Ohms; an open circuit (infinite resistance) or a very low reading close to zero both indicate a faulty element. Also test between each terminal and the machine's metal chassis — any reading other than infinite resistance here indicates the element has shorted to earth and must be replaced.
- 6
Reassemble and run a test cycle
After any inspection or part replacement, refit the rear panel securely, reconnect the machine, and run a 40°C cotton cycle to completion. Monitor the machine during the first 15 minutes when the heater is most active. If E20 does not reappear, the fault is resolved.
- 7
If E20 persists, consider the control board
If all components test within specification but E20 continues to appear, the control board itself is the likely culprit — specifically a stuck heater relay. At this point, further diagnosis requires specialist equipment and the fault should be handed to a service technician.
Affected models
Select your model to see its full troubleshooting page.
When to call a service technician
Contact a service technician if E20 returns immediately after a hard reset, or if your multimeter tests show the heating element and NTC sensor are both within normal specification. A stuck relay on the control board cannot be safely diagnosed or repaired without specialist tools, and attempting to bypass or repair the board without experience risks creating an electrical hazard.
You should also call a technician if you notice any signs of burning smell, scorch marks around the element terminals, or if the machine trips your household circuit breaker when it reaches the heating phase of a cycle. These symptoms suggest an active electrical fault that goes beyond routine DIY repair.
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Frequently Asked Questions
Can I still use my Siemens washing machine while it shows E20?
It is not advisable to continue using the machine until the fault is diagnosed. An unexpected heating fault could mean the element is activating at the wrong time, which risks overheating a cold wash or causing damage to delicate fabrics. It also places unnecessary stress on the control board.
How do I know if the NTC sensor or the heating element is the problem?
Testing both with a multimeter is the most reliable way to tell them apart. The NTC sensor will show an out-of-range resistance reading if it has failed, while a faulty heating element will show either an open circuit or a short to earth. If both test correctly, the control board is the more likely source of the fault.
Is E20 the same fault on all Siemens washing machine models?
The E20 code consistently refers to an unexpected heating or control board fault across Siemens washing machine ranges, but the exact location of components and the steps to access them can vary between models. Always check your specific model's user manual or service documentation before opening the machine.
How much does it typically cost to repair a Siemens E20 fault?
If the fix is a simple power reset, there is no cost at all. Replacing an NTC sensor is generally inexpensive, and a heating element is a mid-range repair. A control board replacement is the most costly outcome, and you should weigh the repair cost against the age and overall condition of the machine before proceeding.
Why does E20 sometimes appear only once and then disappear?
A single occurrence of E20 that does not return after a reset is most often caused by a brief voltage spike or a momentary sensor misread rather than a failed component. However, if it reappears — even weeks later — treat it as a developing fault and carry out the full diagnostic steps, as intermittent faults tend to become permanent over time.