Convotherm Combi Oven Error Code E99.9: Initialization Error
E99.9 on a Convotherm C4 reads Initialization error. Disconnect the unit from the outlet for about 10 seconds and restart it. If the oven shows E99.9 again, it needs a service call.
High: the oven cannot finish starting up and will not cook until the cause is cleared.
- Code
- E99.9
- Maker
- Convotherm
- Equipment
- Combi ovens
- Applies to
- Convotherm 4 (C4 easyTouch / easyDial, incl. Maxx pro)
What does Convotherm error code E99.9 mean?
Every time a combi oven is powered up, it goes through a start-up routine: the main control wakes, loads its settings and checks that the display and the other boards answer. Only after all of that finishes does the oven offer a cooking menu. E99.9 Initialization error means one of those start-up steps did not complete. Because the oven never gets past start-up, it cannot cook, and the screen may start and then stay on the message. The manual's response is the same as for the neighboring communication code: disconnect the unit from the outlet for about 10 seconds and restart it, which gives every board a clean power-up. This clears an interrupted start, such as one that happened when power flickered. If the start-up fails again at the same point, a board, a connector or stored settings are not being read correctly, which is service territory.
Affected models and control systems
Convotherm 4 (C4) floor-standing combi ovens, from the UL / USA operating manual. Table-top and maxx pro models are not named in the text we read.
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
- E99.9 Initialization error right after power-on
- Screen starts, then stays on the message
- Oven will not move on to a cooking menu
- Same message again after each restart
Possible causes
Likely causes — what usually sits behind error code E99.9 on this control. A technician confirms which one it is before any part is replaced.
- Power interrupted or unstable during start-up
- Display or control board connector not seated
- Stored settings that the control cannot read at power-on
- Board that fails its own start-up self-check
Safe checks before calling for service
- Switch the oven off and unplug it from the outlet.
- Wait about 10 seconds, as the manual says.
- Plug it in and start the oven again, giving it time to finish starting.
- If E99.9 appears again, leave it unplugged and contact Customer Service.
- Tell the technician whether the message appears every time or only after power loss.
How a technician diagnoses error code E99.9
- Read E99.9 and the history to see whether the start-up stops at the same point each time.
- Check the supply voltage and breaker at the moment of power-up.
- Inspect the connectors between the display and control boards for looseness.
- Confirm that the control software and stored settings load without errors.
- Replace the board that fails to start only after the supply and connections are verified.
- Start-up failures involve the main control board, which runs at line voltage and holds the oven's own configuration.
- Reloading the oven's settings after a board change needs service tools and the exact model data.
- Repeated power cycling can mask the real cause and stress the boards, so the testing should be done in a controlled order.
How error code E99.9 differs from similar codes
E99 reports a communications dropout while the oven is running; E99.9 stops it at start-up. Both use the same 10-second restart.
Technical reference
- Maker documentation
- Convotherm owner support
- Edition
- 9761695_06 engUSA 05/22
- Models / control
- Convotherm 4 (C4 easyTouch / easyDial, incl. Maxx pro)
- Section
- 6.2.1 Error codes (Errors and required responses), pp. 105
- 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 Convotherm combi oven error codes
Why does the screen come on and then stop on E99.9?
The display powers first, but the oven's start-up check fails before cooking is offered, so the message stays.
Is E99.9 caused by a bad cooking program?
No. That would be a cooking profile code like E81.0. E99.9 happens in the oven's own start-up.
How many times may I restart it?
One careful restart as the manual describes is reasonable. If it fails again, further tries will not help.
Need help with Convotherm error code E99.9?
A technician confirms the cause on site and gives you the price in writing before any work starts.