⚡ TL;DR — Quick Answer

Descale the Bosch Siemens boiler using an approved descalant. Limescale is the #1 cause of heating failures.

What Causes Not Heating?

Bosch and Siemens machines share the same platform and use automatic milk cleaning systems.

Step-by-Step Fix

Follow these steps specifically for Bosch Siemens machines:

  1. Descale the Bosch Siemens boiler using an approved descalant. Limescale is the #1 cause of heating failures.
  2. Test the NTC temperature sensor with a multimeter. On Bosch Siemens machines, a faulty sensor shows infinite resistance.
  3. Inspect the heating element for calcium deposits. If resistance is out of spec, replace the element.
  4. After descaling, run 3 empty brew cycles to purge air from the heating chamber.

Bosch Siemens Pro Tip

Expert advice: EQ.9 users: run the milk system rinse after every milk-based drink.

Model-Specific Notes

These steps apply to: Bosch TIE865, Siemens EQ.9, Siemens TI35, Bosch VeroCup, Siemens TK7. For exact part numbers, consult the Bosch Siemens parts catalog at Bosch Siemens Support.

Preventive Maintenance

Use Siemens/Bosch descalant tablets every 2 months.

Popular Bosch Siemens Models

When to Call a Professional

If these steps don't resolve the issue, contact an authorized Bosch Siemens service center. Complex electrical or hydraulic problems require professional diagnosis.

Frequently Asked Questions

Cold brew means the heating element, its thermostat, or the thermal fuse has failed. Scale builds up inside every coffee machine and eventually blocks the boiler and pipes. Run a full descaling cycle with Bosch Siemens's approved descalant every 2-3 months (or whenever the machine prompts it), then rinse with fresh water. If your machine refuses to descale, see our Not Heating guide.

The quickest way to fix scale problems on a Bosch Siemens is a full descaling run: use the approved descalant, follow the machine's cycle, and finish with two rinse brews. Repeat every 2-3 months, or as soon as the alert appears. Step-by-step instructions are in our Not Heating guide.

If a Bosch Siemens has not been descaled for a while, limescale restricts the boiler and pipes. Buy the brand's descalant, run the descale program, rinse thoroughly, and schedule it every 2-3 months from now on. See our Not Heating guide for the full routine.

A Bosch Siemens prompts for descaling based on water hardness and usage. The fix is simple: run the descale cycle with approved descalant, rinse twice, and use filtered water to make the intervals longer. Details in our Not Heating guide.