Alto-Shaam Combi Oven Error Code E93: Boards in Different States
E93 Interface Board (IB) and Control Board (CB) are in different states means the two boards disagreed about the oven's running state for over 20 seconds. Switch the oven off, remove power, restore it and restart. If E93 returns, a technician should check the CAN cable and connectors.
High: the boards disagree about the oven's state, so the program cannot continue reliably.
- Code
- E93
- Maker
- Alto-Shaam
- Equipment
- Combi ovens
- Applies to
- Combitherm CT PROformance (CTP) and CT Classic (CTC)
What does Alto-Shaam error code E93 mean?
The interface board and the control board each keep track of what the oven is doing, such as idle, cooking or cleaning, and they compare notes over the CAN cable. If they have been in different running states for more than 20 seconds, the interface board posts E93 Interface Board (IB) and Control Board (CB) are in different states. Both boards are alive, but their data does not match, so the oven cannot trust either picture. The manual gives the same remedy as E92: turn the oven off, disconnect power, reconnect and restart. If it returns, the listed causes are the CAN cable, the relay board low voltage connector and the display board connector. A weak connection can drop part of a message and leave the boards out of step. On a CT Express, E93 means a communication error from the display board, which is a different condition.
Affected models and control systems
Combitherm CTP and CTC combis of the six standard sizes, electric and gas. E93 on a CT Express means something different.
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 board states message on the display
- Display showing one mode while the oven does another
- Program stopping partway through
Possible causes
Listed in Alto-Shaam's documentation
- CAN cable malfunction
- Relay board low voltage 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.
- An intermittent connector that drops messages only when the oven warms up or vibrates
- A board that restarted alone after a power dip, leaving it behind the other
Safe checks before calling for service
- Turn the oven off at its switch or breaker and wait about a minute.
- Switch it on again and start a short program.
- Watch whether the display matches what the oven is doing.
- If E93 returns, write down what mode it was in and how long the oven had been on.
How a technician diagnoses error code E93
- Read the code and the sequence of events before it.
- Check the CAN cable and both connectors for seating and corrosion.
- Check the relay board low voltage connector and the display board connector.
- Verify steady supply voltage to the control electronics.
- Replace or reflash a board only after the wiring is proven good.
- The connectors are behind the panel near live wiring.
- Board replacement needs matching software and settings.
- Intermittent link problems are found by testing under heat and vibration.
How error code E93 differs from similar codes
E92 is the control board not answering, E94 is no signal for 20 seconds, and E93 is both talking but disagreeing on state.
Technical reference
- Maker documentation
- Alto-Shaam owner support
- Edition
- MN-35949 Rev 08 03/22
- Models / control
- Combitherm CT PROformance (CTP) and CT Classic (CTC)
- Section
- Error Codes, pp. 25-31
- 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 more serious than E92?
Not necessarily; both use the same restart and the same three causes.
Can the display be wrong?
It may show a state that the control board is not in.
Do I need new boards?
Usually a cable or connector is found first.
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.