Alto-Shaam Combi Oven Error Code E56: Vent 2 Not Open
E56 Vent 2 Not Open means the upper vent on a dual-vent oven did not open within 60 seconds of its motor starting. Press the Start icon to acknowledge it and ask for a vent check.
Medium: venting is affected on one vent but cooking may continue.
- Code
- E56
- Maker
- Alto-Shaam
- Equipment
- Combi ovens
- Applies to
- Combitherm CT PROformance (CTP) and CT Classic (CTC)
What does Alto-Shaam error code E56 mean?
Dual-vent combi ovens have two motor-driven vent valves, and each has a monitoring switch that proves the vent has opened. The control starts the upper vent motor and waits for the switch. If the switch has not opened after 60 seconds, it posts E56 Vent 2 Not Open. The manual says this is the same as E55, only for the upper vent. It lists the same two causes: the vent valve monitoring switch has failed, or the vent valve motor has failed. Pressing Start acknowledges the message and the oven then tries to return to normal operation, but the upper vent check repeats at the next venting call. If only one vent is stuck, the other vent may still move some air, but the oven treats a vent that cannot prove it has opened as a problem. Wet, greasy air passes through this area, so residue is a practical reason for a slow vent.
Affected models and control systems
Alto-Shaam Combitherm CT PROformance and CT Classic combi ovens with dual vents, such as the larger roll-in sizes. Single-vent ovens use E55 for their one vent.
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
- E56 Vent 2 Not Open on the display
- Steam lingering in the cavity after a steam program
- Upper vent not moving when the oven vents
Possible causes
Listed in Alto-Shaam's documentation
- Vent valve monitoring switch malfunction
- Vent valve motor malfunction
Other likely causes — what usually sits behind error code E56 on this control. A technician confirms which one it is before any part is replaced.
- Grease and mineral deposit around the upper vent flap slowing it
- A bent flap or loose crank arm that the motor turns without moving the flap
Safe checks before calling for service
- Press the Start icon once to acknowledge E56.
- Check the upper vent opening on the outside of the oven for blockage.
- Let the oven cool before looking for visible buildup.
- If E56 returns, tell the technician whether E55 also appeared.
How a technician diagnoses error code E56
- Read the code and check for E55.
- Run the upper vent motor and watch for flap movement.
- Test the monitoring switch for continuity at open and closed positions.
- Check the linkage and clean away residue.
- Replace the upper motor or switch after finding which one fails.
- The vent motors are part of live control wiring.
- Cleaning and testing the vent assembly needs the cavity cooled and panels off.
- Both vents must be proven before the oven can vent properly.
How error code E56 differs from similar codes
E55 covers a single vent or the lower vent; E56 is the upper vent on dual-vent models.
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
Which vent is Vent 2?
The upper vent of a dual-vent oven.
Do I need a technician for both E55 and E56?
Each vent has its own motor and switch, so both are checked.
Can E56 clear by itself?
Only if the vent moves again; a stuck vent returns it.
Need help with Alto-Shaam error code E56?
A technician confirms the cause on site and gives you the price in writing before any work starts.