Alto-Shaam CT Express Combi Error Code E27: Element Too Hot
E27 N8 Immersion Element Temperature Too High means the immersion element in the steam boiler is too hot. A technician should descale the generator and level probe and check the contactor and N8 probe.
High: an element that is too hot can damage the boiler, so steam cooking should stop.
- Code
- E27
- Maker
- Alto-Shaam
- Equipment
- Combi ovens
- Applies to
- Combitherm CT Express / ESi / CCi (older 4-10 and 4.10 units; boiler or generator electric/gas)
What does Alto-Shaam error code E27 mean?
The CT Express makes steam with an immersion element, and probe N8 watches its temperature. In normal use, water covers the element and carries the heat away. If N8 reports the element is too hot, the control posts E27 N8 Immersion Element Temperature Too High, which the manual's display list calls Boiler Element Temperature High. The manual lists three causes: scale in the steam generator or on the level probe, an immersion element contactor stuck closed, and a defective N8 probe. Scale insulates the element and the level probe, so the element can overheat even when the boiler is full or the level reading is wrong. A stuck contactor keeps power on the element when it should be off. This number is specific to the CT Express; on CT PROformance and CT Classic ovens E27 means sensing point 2 of the core probe.
Affected models and control systems
CT Express models 4-10ESi, 4-10ESiVH, 4-10CCi, CTX4-10E, CTX4-10EC and CTX4-10EVH. The other Combitherm series assign E27 to a different message.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- E27 N8 Immersion Element Temperature Too High on the display
- Steam output dropping before the message
- Boiler stopping heating
Possible causes
Listed in Alto-Shaam's documentation
- Scale in the steam generator or on the level probe
- Immersion element contactor stuck closed
- Defective N8 probe
Other likely causes — what usually sits behind error code E27 on this control. A technician confirms which one it is before any part is replaced.
- Hard water scaling the element faster than the descale schedule allows
- A filter or softener that stopped treating the water
Safe checks before calling for service
- Turn the oven off and let it cool.
- Avoid running steam programs.
- Check when the boiler was last descaled and the water filter changed.
- Tell the technician the dates, and any steam output drop beforehand.
How a technician diagnoses error code E27
- Read the code and ask about descale history.
- Inspect the boiler and level probe for scale with the oven cool.
- Descale the boiler and probe as the manual directs.
- Check the immersion element contactor for stuck contacts.
- Test N8 and replace it only if it fails.
- The immersion element is a high-current heater in a hot boiler.
- Descaling uses acid cleaners.
- A stuck contactor keeps live power on the element.
How error code E27 differs from similar codes
E26 on the CT Express reports N8 open; E27 reports the element too hot. On other Combitherm series these numbers mean core probe sensing points.
Technical reference
- Maker documentation
- Alto-Shaam owner support
- Edition
- MN-36008 (Rev. 9) 03/16
- Models / control
- Combitherm CT Express / ESi / CCi (older 4-10 and 4.10 units; boiler or generator electric/gas)
- Section
- Section C, Error Codes, pp. C-3 to C-8
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related Alto-Shaam combi oven error codes
Is scale the main cause?
It heads the manual's list, with the contactor and probe after it.
Is E27 the same as E13?
They are alike in idea, but E13 is the steam generator on CT PROformance and Classic ovens.
Can I keep steaming?
No, the element should not run hot.
Need help with Alto-Shaam error code E27?
A technician confirms the cause on site and gives you the price in writing before any work starts.