Alto-Shaam CT Express Combi Error Code E101: Relay Board Version
E101 means the relay board (RB) found that its software version differs from the display board (DB). Perform the software update again, and check the ribbon cable, compact flash card and connectors.
High: mismatched board software can stop the oven from starting.
- Code
- E101
- 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 E101 mean?
This is the same mismatch as E100, seen from the other side. The relay board (RB) runs the oven's heaters, valves and motors, and the display board (DB) runs the screen. Each has a software version, and the two must match. When the relay board does the checking and finds a difference, it posts E101 DB version is not equal to RB version. Error generated by RB. The manual lists four causes: a failed software update, a defective ribbon cable, a defective compact flash card, and defective board connectors. Which board raises the message tells a technician which board started the check, so having both E100 and E101 in the history suggests the boards cannot agree at all. The manual's remedy is the same: perform the software update again. On CT PROformance and CT Classic ovens, E101 means the ventless hood power or pressure switch is not closed, which is a different condition.
Affected models and control systems
Combitherm CT Express models 4-10ESi, 4-10ESiVH, 4-10CCi, CTX4-10E, CTX4-10EC and CTX4-10EVH; on other Combitherm series E101 means a ventless hood problem.
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
- E101 board version message on the display
- Oven refusing to start after a software update
- Message returning with each power-up
Possible causes
Listed in Alto-Shaam's documentation
- Failed software update
- Ribbon cable defective
- Compact flash card defective
- Board connectors defective
Other likely causes — what usually sits behind error code E101 on this control. A technician confirms which one it is before any part is replaced.
- A relay board replaced with a different software version than the display board
- A compact flash card with an older update file than the installed boards
Safe checks before calling for service
- Turn the oven off and on once.
- Do not open the control panel or remove the card.
- Note any recent board replacement or software update.
- Tell the technician if E100 also shows.
How a technician diagnoses error code E101
- Read the code and see whether E100 shows too.
- Check the software version on each board.
- Run the software update again from a good compact flash card.
- Inspect the ribbon cable and connectors.
- Replace the card, cable or board only after the update is retried.
- Board work happens behind a panel with live voltage.
- Software must match the oven's model and settings.
- A failed update can leave a board unusable.
How error code E101 differs from similar codes
E100 and E101 are the same mismatch raised by different boards; CT PROformance and Classic ovens use E101 for the ventless hood.
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
Why two codes for one problem?
Each board can detect the mismatch, and the number says which one did.
Does E101 always mean a bad board?
No. A failed update is the first cause listed.
Is this the ventless hood E101?
No, that is on other Combitherm series.
Need help with Alto-Shaam error code E101?
A technician confirms the cause on site and gives you the price in writing before any work starts.