How to check the temperature sensor in a Bosch washing machine

How to check the temperature sensor in a Bosch washing machine

The need to check the temperature sensor in a Bosch washing machine arises in two cases: if the machine has stopped washing in hot water or, on the contrary, overheats to unplanned degrees. It is the thermistor that is “responsible” for heating to specified limits, activating, or turning off the heating element. In the event of failures, the first thing to do is test it, and if it malfunctions, replace it. We will tell you how and what to do point by point.

Finding and testing the sensor

In modern Bosch models, the temperature sensor is a metal tube 3 cm long and 1 cm in diameter. The thermistor is located on the body of the heating element, “held” by several wires and bolts. Heating of water to a given temperature is carried out by changing the resistance in the sensor.

To check the thermistor for functionality, you need to remove it from the washing machine along with the heating element. First, we disconnect the machine from the power supply, and then proceed to disassemble it. We proceed according to the following instructions:

  • Unhook the back panel of the washing machine from the body,
  • We find the “trick” of the heating element - a rounded plate under the drum with connected wiring,
  • We photograph the location of the wires so as not to make a mistake during reassembly,
  • Disconnect the wires from the heater,
  • Loosen the central screw,
  • Rocking the body of the heating element, we remove it from the machine.

Now we loosen the fasteners holding the temperature sensor and disconnect it from the heating element. Next, we proceed to check the device using a multimeter:

  • Set the tester to “Resistance” mode,
  • Connect the probes to the contacts,
  • Lower the sensor into hot water (the contacts must not be wet!).
  • We evaluate the readings on the device.

The value that appears is compared with the norm. So, when immersed in water with a temperature of 100 degrees, the thermostat will show about 6000 Ohms. As the liquid cools, the number will drop, and as it heats up, it will rise. If the result is far from ideal or does not change, then the thermostat is faulty. The device cannot be repaired - only replaced with a new one.

A new temperature sensor can be purchased at a specialized store or ordered online directly from the manufacturer. To avoid mistakes, you need to show the seller the old device. Then we install the thermostat in the washing machine and return everything to its place, proceeding in the reverse order.

How does the breakdown manifest itself?

High-quality and complete washing is possible only with a working thermistor. With it, the machine heats the water strictly to the specified temperature, without threatening things or itself. If there is a malfunction in the sensor, the machine will become “strange.” In the best case, it will stop heating water at high temperatures, in the worst case, it will lead to the combustion of the heating element.

You can suspect a breakdown of the temperature sensor based on several signs:

  • When the mode is started at 60-90 degrees, the hatch glass remains cold after 15-20 minutes of the cycle,
  • With any program, even fast and delicate, the machine heats the water to boiling water,
  • When washing, the machine gets very hot and hot steam comes out of the door.

It is dangerous to ignore such behaviour of the machine. A faulty thermistor can lead to overheating of the heating element until it burns out. The cost of a new heater is several times higher than the sensor, so it is better not to delay replacement and immediately respond to heating problems.