Alto-Shaam CT Express Combi Error Code E93: Display Link Error
E93 Communication Error, FROM Display Board means the display board and the low-voltage relay board are not communicating. A technician should check the ribbon cable, its connections and the board connectors.
High: the display and relay boards cannot talk, so the oven may not respond.
- Code
- E93
- 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 E93 mean?
On the CT Express, the display board and the low-voltage relay board talk to each other over a ribbon cable. If the messages stop arriving, the control posts E93 Communication Error, FROM Display Board. The manual lists four causes: loose or defective ribbon cable connections, a defective ribbon cable, a defective relay board connector, and a defective display board connector. All four are links in the same chain, so the problem is almost always a connection rather than a board. This is a different message from E93 on the CT PROformance and CT Classic ovens, where the same number means the interface and control boards are in different states over a CAN cable. The manual's action is for a technician only. The display may freeze or go blank when the link drops, and the oven may stop responding to keys.
Affected models and control systems
The CT Express line (4-10ESi, 4-10ESiVH, 4-10CCi, CTX4-10E, CTX4-10EC, CTX4-10EVH). A CT PROformance or CT Classic gives E93 another meaning.
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
- E93 Communication Error on the display
- Display freezing or blank
- Keys not responding
Possible causes
Listed in Alto-Shaam's documentation
- Ribbon cable connections loose or defective
- Ribbon cable defective
- Relay board connector defective
- Display board connector defective
Other likely causes — what usually sits behind error code E93 on this control. A technician confirms which one it is before any part is replaced.
- A ribbon cable stressed where the control panel hinges open
- Corrosion at a connector from steam or cleaning spray
Safe checks before calling for service
- Turn the oven off, wait a minute, and turn it on again.
- Do not spray water at the control panel.
- Note whether the display works for a while after start-up.
- If E93 returns, tell the technician when it appears and whether the panel was cleaned.
How a technician diagnoses error code E93
- Read the code and confirm the restart was tried.
- Inspect the ribbon cable and its connectors for seating and damage.
- Check the relay board and display board connectors for corrosion.
- Check the supply to both boards.
- Replace the cable first, then boards if needed.
- The cable and boards sit behind the control panel with live low and line voltage.
- Static damage to boards is easy to cause.
- A replaced board may need its settings loaded.
How error code E93 differs from similar codes
On CT PROformance and CT Classic ovens E93 is a CAN-link state mismatch; on the CT Express it is a ribbon-cable error from the display board.
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 E93 the same on every Combitherm?
No, the CT Express uses a ribbon cable and the others a CAN cable.
Will restarting help?
Maybe for a glitch, but connections usually need to be checked.
Is the display broken?
More likely a cable or connector.
Need help with Alto-Shaam error code E93?
A technician confirms the cause on site and gives you the price in writing before any work starts.