Why Is My Bosch Washing Machine Not Heating the Water?
Run a 60°C cotton cycle with no laundry and check whether the drum feels warm partway through — if it does not, reset the machine by switching it off at the wall for 60 seconds and restarting; this clears temporary control board faults and resolves the issue in a small but meaningful number of cases (takes about 5 minutes).
Fault description
When a Bosch washing machine fails to heat water, the wash cycle still runs from start to finish, but the water inside the drum stays at or near room temperature regardless of the programme temperature you selected. Clothes may come out still smelling stale, greasy marks may not lift, and biological detergents — which rely on warm water to activate enzymes — will perform poorly.
The heating system in a Bosch washing machine consists of a heating element, a temperature sensor (NTC thermistor), and the control board that interprets sensor readings and switches the element on and off. A fault in any one of these components can prevent heating entirely. Related error codes E60 through E69 may appear on the display, each pointing to a slightly different part of the heating circuit, but the underlying diagnosis process is largely the same.
Because this fault involves electrical components that carry mains voltage, some steps below require a multimeter and basic electrical confidence. If you are not comfortable working with internal wiring, skip to the section on calling a service technician.
Causes
- Failed heating element — The heating element is the most common reason a Bosch washing machine stops heating. Over time, the element burns out or develops an internal break, preventing it from generating heat even when the control board sends the correct signal.
- Faulty NTC temperature sensor (thermistor) — The NTC sensor monitors water temperature and reports back to the control board. If it fails or drifts out of calibration, the board may believe the water is already hot and never switch the element on — error codes E61, E62, and E65 are commonly linked to this component.
- Control board fault — The main PCB controls when power is sent to the heating element. A damaged relay or failed triac on the board can interrupt this signal, leaving the element permanently off even though it is physically intact. Codes E66, E67, and E68 often point here.
- Wiring harness damage or loose connection — Vibration over years of use can loosen the connectors between the heating element, the NTC sensor, and the control board. A partially disconnected or corroded terminal can mimic a component failure without any part actually being broken.
- Heavy limescale build-up on the element — In hard-water areas, limescale coats the element and acts as an insulator, reducing heating efficiency dramatically. In severe cases the element overheats locally and burns out, triggering protective cut-outs and codes such as E63 or E64.
- Thermal cut-out (thermal fuse) tripped or blown — Bosch machines include a thermal cut-out that protects the element from overheating. If it has tripped due to a previous overheating event, the element will receive no power until the cut-out is replaced or reset.
Step-by-Step Fix
- 1
Check the programme selection and display for error codes
Confirm you have selected a programme that actually heats water — a cold rinse or a 20°C eco cycle will not heat. Note any error code on the display (E60–E69) before clearing it, as this narrows down which component to inspect first. Consult your model's manual to confirm what each code means for your specific machine.
- 2
Reset the machine and run a test cycle
Switch the machine off at the wall socket and leave it unpowered for 60 seconds. Restart and select a 60°C cotton programme. About 15–20 minutes into the cycle, carefully open the detergent drawer and feel the water entering the drum — it should be noticeably warm. This rules out a temporary control board glitch before you start disassembling anything.
- 3
Inspect and test the NTC temperature sensor
Disconnect the machine from the mains. The NTC sensor is usually clipped to the heating element housing at the rear or front lower section of the drum. Unplug its connector and measure resistance with a multimeter — at room temperature (around 20°C) a healthy NTC typically reads 4,000–6,000 ohms. A reading of zero or infinity indicates a failed sensor that needs replacing.
- 4
Test the heating element for continuity
With the machine still unplugged, locate the heating element terminals (accessible from the rear panel on most Bosch models). Set your multimeter to resistance and probe the two main terminals — a working element typically reads between 20 and 50 ohms. An open circuit (infinite resistance) confirms the element has burned out and must be replaced. Also check that neither terminal shows continuity to the machine's metal casing, which would indicate a short to earth.
- 5
Check the thermal cut-out
The thermal cut-out is a small disc or capsule mounted directly on or very close to the heating element. Test it for continuity with your multimeter — it should read close to zero ohms when healthy. If it reads open circuit, it has blown and needs to be replaced. Investigate why it tripped (usually limescale or a failing element) before fitting a new one, or it will blow again.
- 6
Inspect wiring connectors to the element and sensor
With the machine unplugged, trace the wiring from the heating element and NTC sensor back toward the control board. Look for connectors that have pulled loose, terminals that are corroded or discoloured, and any wiring that shows signs of heat damage or chafing. Reseat any loose connectors firmly and replace any damaged sections of harness before reassembling.
- 7
Assess the control board
If the element, NTC sensor, thermal cut-out, and wiring all test as healthy, the fault is most likely on the control board itself — specifically a failed relay or triac that switches power to the element. Visually inspect the board for burn marks, swollen capacitors, or cracked solder joints. Control board replacement or repair is the final step and is best carried out by a service technician unless you have experience with PCB-level work.
When to call a service technician
Call a service technician if you have tested the heating element, NTC sensor, and thermal cut-out and all appear electrically sound, yet the machine still does not heat. This pattern strongly suggests a control board fault — replacing or repairing a PCB involves mains-voltage circuitry and, on Bosch machines, may also require software configuration after fitting a new board.
You should also seek professional help if you find burn marks inside the machine, smell burning during a cycle, or if the machine trips your household circuit breaker when it attempts to heat. These signs indicate a potentially dangerous electrical fault that goes beyond routine component replacement.
Prevention
The parts most commonly replaced when a Bosch washing machine stops heating are the heating element, the NTC temperature sensor, and the thermal cut-out fuse. Using a descaling tablet every three to six months (more frequently in hard-water areas) significantly extends element life by preventing the limescale build-up that causes premature burnout. Always use the correct amount of detergent and avoid consistently running only cold or 30°C cycles, as occasional higher-temperature washes help keep the element free of residue.
If you need to replace any of these components, use genuine Bosch-compatible parts matched to your model number to ensure correct resistance ratings and a proper fit.
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Frequently Asked Questions
What do error codes E60 to E69 mean on a Bosch washing machine?
These codes all relate to the heating circuit. E60 is a general heating fault, E61–E65 typically indicate NTC sensor or temperature-reading problems, and E66–E69 usually point to the control board or the element circuit itself. Note the specific code before clearing it, as it helps narrow down which component to test first.
Can I still use my Bosch washing machine if it is not heating?
You can run the machine safely on a cold wash in the short term, but it is not a long-term solution. Washing at cold temperatures will not kill bacteria effectively, biological detergents will not activate properly, and the underlying fault — particularly if it involves a partially failed element — could worsen and eventually cause the machine to trip your electrics.
How do I know if my heating element has burned out rather than the sensor?
Test both with a multimeter. A burned-out element will show infinite resistance (open circuit) between its two main terminals. A failed NTC sensor will show either infinite resistance or zero resistance rather than the expected 4,000–6,000 ohms at room temperature. Testing both takes about 20 minutes and tells you exactly which part to order.
Is a Bosch washing machine heating fault worth repairing, or should I replace the machine?
In most cases it is worth repairing. A heating element and NTC sensor are relatively low-cost parts, and fitting them is straightforward on most Bosch models. Even a control board replacement is usually cheaper than a new machine. The decision changes if the machine is over ten years old and has other developing faults — at that point a service technician can give you an honest assessment.
Could hard water cause my Bosch washing machine to stop heating?
Yes. In hard-water areas, limescale accumulates on the element surface and acts as an insulator, forcing the element to work harder and run hotter until it eventually burns out or triggers the thermal cut-out. Running a dedicated washing machine descaler every three months is one of the most effective ways to prevent heating faults and extend the life of the element.