What Does Error Code E20 Mean on a Bosch Washing Machine?
Power cycle the machine by switching it off at the wall, waiting 5 minutes, then switching it back on and restarting the programme — this clears temporary control board errors and resolves the fault in many cases (takes about 5 minutes).
Fault description
Error code E20 signals that your Bosch washing machine's control board has detected heating activity when it shouldn't be occurring, or that the heating circuit is behaving in an unexpected way. This is classified as a control board fault because the board is responsible for monitoring and authorising when the heating element switches on and off during a wash cycle.
When E20 appears, the machine will typically pause mid-cycle or refuse to start a new programme. In some cases you may notice the drum filling with water but the cycle not progressing, or the machine stopping shortly after the wash phase begins. The display will show E20 and the machine will lock out further operation until the fault is addressed.
This fault can stem from a genuine electrical component failure, but it is also frequently triggered by a temporary software glitch in the control board — meaning a simple reset is always worth trying first before investigating further.
Causes
- Temporary control board software glitch — The control board can occasionally misread sensor data or lose its programme state, causing it to flag a heating fault incorrectly. A power cycle clears the board's memory and resolves this without any parts replacement.
- Faulty NTC temperature sensor — The NTC sensor monitors water temperature and feeds readings back to the control board. If the sensor is sending incorrect or erratic readings, the board may interpret this as unexpected heating and trigger E20.
- Heating element failure or short circuit — A heating element that has partially failed or developed an internal short can activate outside of its normal cycle window. The control board detects this irregular behaviour and raises the E20 fault to prevent overheating.
- Wiring harness damage between the heating circuit and control board — Loose, corroded, or damaged wiring connecting the heating element, NTC sensor, or relay to the control board can cause false signals. This can make the board believe heating is occurring when it is not, or vice versa.
- Faulty control board (PCB) — If the relay on the control board that switches the heating element on and off has failed in the closed position, the element may receive power continuously. This is a less common but serious cause that typically requires board replacement.
Step-by-Step Fix
- 1
Power cycle the washing machine
Turn the machine off using the power button, then switch it off at the wall socket. Leave it unplugged for at least 5 minutes to allow the control board to fully reset. Plug it back in, select a short programme such as a quick wash, and observe whether E20 returns.
- 2
Check for any active error history and note the conditions
Before dismantling anything, note when E20 appeared — was it at the start of the cycle, during the wash phase, or during rinse? This helps narrow down whether the fault is heating-related or sensor-related. If the error only appears on hot wash programmes, the heating element or NTC sensor is more likely to be involved.
- 3
Inspect the wiring connections to the heating element and NTC sensor
Disconnect the machine from the mains before doing this. Remove the rear panel to access the heating element, which is located at the bottom of the drum. Check that all connectors are firmly seated and look for any signs of burning, corrosion, or broken wires. Reseat any loose connectors and replace any visibly damaged wiring.
- 4
Test the NTC temperature sensor
Using a multimeter set to resistance (ohms), disconnect the NTC sensor connector and measure across its two terminals. At room temperature, a healthy NTC sensor typically reads between 10,000 and 20,000 ohms depending on the model. A reading of zero, infinity, or wildly outside this range indicates a faulty sensor that should be replaced.
- 5
Test the heating element for continuity and insulation
With the machine unplugged, disconnect the heating element terminals and use a multimeter to check for continuity across the two main terminals — you should get a reading of roughly 20–30 ohms. Also check between each terminal and the machine's metal chassis; any continuity here indicates an earth fault and the element must be replaced.
- 6
Replace the NTC sensor or heating element if faulty
Both parts are accessible from the rear of the machine. The NTC sensor clips into the heating element housing and is straightforward to swap out. The heating element requires draining the drum and removing the element retaining nut. Use only genuine Bosch-compatible parts to ensure correct resistance and temperature ratings.
- 7
If the fault persists after replacing sensors and the element, suspect the control board
A control board with a stuck heating relay will continue to trigger E20 regardless of other repairs. At this stage, further diagnosis requires specialist equipment to test the relay and board circuits. This is the point at which calling a service technician is the most practical and cost-effective route.
Affected models
Select your model to see its full troubleshooting page.
When to call a service technician
If you have completed a power cycle, inspected the wiring, and tested or replaced the NTC sensor and heating element but E20 continues to appear, the fault is most likely within the control board itself. A failed relay or damaged PCB track cannot be reliably diagnosed or repaired without specialist tools and component-level knowledge.
You should also call a service technician immediately if you notice any burning smell, scorch marks around the heating element area, or signs of water leaking near electrical components. These symptoms indicate a risk of further damage or a safety hazard that goes beyond routine DIY repair.
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Frequently Asked Questions
Can I still use my Bosch washing machine while it shows E20?
It is not advisable to continue using the machine with an active E20 fault. The error indicates the heating circuit is behaving unexpectedly, which could mean the element is running continuously. This risks overheating the water, damaging laundry, or causing further electrical damage to the control board.
How do I clear the E20 error code on a Bosch washing machine?
The most reliable way to clear E20 is to switch the machine off at the wall for 5 minutes, then restart it. If the underlying fault has been resolved — whether by a reset, a sensor replacement, or an element swap — the code will not return. If it reappears immediately, the root cause has not yet been fixed.
Is the E20 fault covered under Bosch warranty?
If your machine is within its standard warranty period and the fault is due to a manufacturing defect rather than accidental damage or misuse, Bosch should cover the repair. Contact Bosch customer support directly with your model number and proof of purchase before attempting any DIY repairs, as self-repair may affect your warranty.
How much does it typically cost to repair a Bosch E20 fault?
If the fix is a power cycle or a new NTC sensor, costs are minimal — sensors typically cost between £10 and £25. A replacement heating element usually costs £20–£50 for the part. If the control board needs replacing, parts alone can range from £80 to £200 depending on the model, plus labour if a service technician carries out the work.
Could a blocked filter cause the E20 error on a Bosch washing machine?
A blocked pump filter is not a direct cause of E20, which is specifically a heating circuit fault. However, a heavily restricted machine can sometimes cause the control board to behave erratically. It is still good practice to check and clean the pump filter as part of general maintenance, but it is unlikely to resolve an E20 fault on its own.