Mr
Hi we have a Bosch classixx 1400 water getting very hot, replaced temp sensor in the bottom of drum but still heating past the correct temperature. Any one come across this problem
many thanks
Solution Summary
AI-generated from this discussion
This thread was marked as solved. Here's a summary of the problem and the fix, generated from the discussion below.
Bosch Classixx 1400 overheating water despite new temperature sensor
- The problem
- A Bosch Classixx 1400 washing machine was reported to be heating the water far beyond the selected temperature. The temperature sensor at the bottom of the drum had already been replaced, but the overheating remained.
- Likely cause
- The strongest diagnosis given was a fault elsewhere in the heating control circuit rather than the NTC itself. The discussion particularly suggested a sticking or welded heater relay on the main control board as a realistic cause. Other possible causes mentioned were heater insulation leakage to earth, wiring or connector faults between the NTC, heater and PCB, or an incorrect-spec replacement sensor.
- What fixed it
- Recommended action was to isolate the appliance from the mains, then check the heater for insulation leakage to earth with proper test equipment, inspect wiring and connectors between the NTC, heater and control board, and verify the replacement sensor is the correct Bosch specification. If those checks do not identify the fault, the main control board/heater relay was the most strongly supported suspect. Further diagnosis should be carried out by a suitably qualified appliance engineer.
- Checks to try
- Temperature sensor at the bottom of the drum had already been replaced
- Suggested check of heater for insulation leakage to earth with proper test equipment
- Suggested inspection of wiring and connectors between NTC, heater and main PCB
- Suggested verification that the replacement sensor is the correct specification
- Suggested noting whether overheating happens from the start or only during wash
- Parts or tools mentioned
- temperature sensor (NTC)
- heater
- main control board
- heater relay
- meter
Safety: Isolate the washing machine from the mains before internal checks. Further diagnosis should be carried out by a suitably qualified appliance engineer.
1 Answer
Yes, this can happen, and if a new NTC/temperature sensor hasn’t cured it the fault is usually elsewhere in the heating control circuit.
Before checking anything internal, isolate the washing machine from the mains.
1. Check the heater isn’t partially shorting to earth A heater can sometimes overheat or behave oddly if it is breaking down, even if it still “works”. If you have a meter, the heater should be checked for insulation leakage to earth with the proper test equipment. A standard multimeter often won’t show this properly.
2. Inspect the wiring between NTC, heater and main PCB Look for damaged plugs, corrosion, loose connections or broken wires, especially around the bottom of the tub and where the loom flexes. If the control board is not getting the correct NTC signal, it may keep heating too long.
3. Consider the main control board/heater relay A sticking or welded heater relay on the PCB is a common cause of overheating. If the relay contacts are sticking closed, the heater can remain energised longer than it should. On many Bosch machines this is a realistic possibility if the sensor has already been replaced.
4. Double-check the replacement sensor is correct Pattern parts can sometimes have the wrong resistance curve. If it’s not a genuine or correct-spec Bosch NTC, the board may read temperature incorrectly.
5. Note exactly when it overheats Does it heat constantly from the start, or only go too hot during wash? That helps tell the difference between a relay stuck on and a sensing/control fault.
If you’re not equipped to test live/heating circuits or the PCB, I’d strongly recommend a qualified appliance engineer, as this involves mains-powered components. WhitegoodsHelp AI
WhitegoodsHelp AI Assistant
This answer was generated automatically by the WhitegoodsHelp AI Assistant. It is not provided by an engineer or any other qualified person, may be inaccurate or incomplete, and is not professional or technical advice. Do not rely on it. Always use your own judgement and consult a qualified engineer before carrying out any electrical, gas or water work. Use is entirely at your own risk. See our full Terms of Use.
SAFETY FIRST: READ BEFORE ACTING ON THIS GUIDANCE
Never work on a live appliance
Always unplug it at the mains before going near it with any tools.
Never attempt gas work
By law, gas appliances must only be worked on by a Gas Safe registered engineer. If your fault involves gas, stop and call a professional. Do not attempt it yourself.
Watch for sharp edges
Outer panels are smooth, but internal parts have sharp machined edges. Wear protective gloves and arm sleeves.
Water appliances can leak
Turn off the water supply before disconnecting any hoses.
Know your limits
If you are not confident testing or working inside the appliance, stop and call a professional.
AI guidance, not guaranteed
This response is generated automatically by the WhitegoodsHelp AI Assistant. It is not professional or technical advice, may be incomplete or wrong, and must not be relied upon. Always use your own judgement and consult a qualified engineer before any electrical, gas or water work.
This is general information only and is not professional advice. The WhitegoodsHelp AI Assistant is not an engineer and is not qualified. See our full Terms of Use.
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