Neff, Siemens, Bosch Cooker Hood Fault Finding & Diagnostic Repair

by / Wednesday, 29 May 2024 / Published in Cooker Hood, Lights & Fittings

How to Repair a Bosch Cooker Hood Faults & Replace Parts?

In this complete guide, we will give you useful tips on repairing cooker hoods by brands such as Bosch, Neff, Siemens, and other manufacturers from the Bosch group. We'll guide you through the process of diagnosing and solving the problem with your cooker hood. The issue the cooker hood in the video is experiencing is a non-functioning bulb, and we'll demonstrate how to replace it.


We would recommend you watch our video since we're showing related components and possible problems with the cooker hood extractor.

Additionally, you can visit our web store to buy genuine spare parts:



Safety First!

  • Unplug your electrical appliance before starting work.



Model Number Identification

Before proceeding, it's crucial to understand the importance of the identification plate located behind the wire mesh. This plate displays the full ER number, which is the manufacturer's model code. This information is vital because parts vary across different types of cooker hoods, and you must ensure that the model number matches the part you're purchasing.

Please remember that the whole video includes step-by-step and detailed explanations, which may help you reduce your repair time.



Understanding the Filters

The metal filter, designed to trap ascending grease, is washable. Some people suggest cleaning them in dishwashers or using abrasive chemicals. However, the most effective cleaning method is using hot soapy water. The meshes vary, with some made of aluminium and others of stainless steel. Using caustic materials on aluminium meshes may discolor them, leaving them unattractive. Stainless steel meshes, on the other hand, can withstand chemicals.

If the cooker hood is recirculating the air within the house instead of venting it outside, it will require a carbonized filter. These filters are available for purchase on our website. They are designed to absorb odors, and it's recommended to replace them every four to six months for optimum performance.



Replacing the Bulb

Before starting any repair work, always disconnect the appliance from the electrical supply. Removing the glass covers requires caution as they are delicate. Use a small screwdriver to gently release the three catches holding the glass in place. Take care not to break the fragile glass.

After removing the glass, you can extract the bulb to test it with a multimeter for continuity or replace it. It's important to note that some bulbs are 230 or 240 volts, while others are low voltage. Identifying whether your bulb holder is 220 to 240 volts (for the UK and Europe) or low voltage is crucial.

Low voltage bulbs have an accompanying transformer that converts the 240 AC voltage to a DC voltage of 12 or 24 volts. Handle halogen bulbs carefully, avoiding direct contact with your fingers as this can cause hot spots on the bulb, leading to premature failure.

After inserting the new bulb, test it by plugging the appliance back into the power supply. If the bulb is in good condition but fails to light up, the issue might be with the switch, the transformer (if it's a low voltage or DC voltage), or the circuit board.



Fault Finding on the Electrical Circuit

Now, we'll disassemble the cooker hood to help you understand the components and make the necessary repairs. You'll get a better understanding of the switch pack, the transformer, and the circuit board.

The switch pack is usually made up of a bank of switches that control the fan speed and light. If the light switch is faulty, it can prevent your bulb from illuminating.

The transformer, used in low voltage bulbs, can also cause problems. It could be that the transformer is no longer converting the voltage correctly, causing the bulb to remain dark.

Lastly, the circuit board could be the culprit. This circuit board controls the electric current to the bulb and other components. If it's faulty, it can cause the bulb to malfunction.

Again, our video includes step-by-step and detailed explanations. If you don't want to make mistakes during the replacing and dismantling process, you can watch our helpful video guide to ease your mind.


Remember, safety should always be your primary concern when working with electrical appliances. If you're still experiencing issues after these steps, we recommend contacting a professional for further assistance.



If you need any parts for your cooker hood, you can find them on our site.

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