Convotherm Combi Oven Error Code E99.x: General Initialization Error
E99.x on the older Convotherm OES, OEB, OGS and OGB ovens is a general initialization error. Unplug the appliance for about 10 seconds and restart it. If an E99 code returns, the oven needs a service call.
High: the oven cannot finish starting and will not cook until the start-up check passes.
- Code
- E99.x
- Maker
- Convotherm
- Equipment
- Combi ovens
- Applies to
- Convotherm OES / OEB / OGS / OGB (older, pre-C4)
What does Convotherm error code E99.x mean?
When the oven is switched on, the main control runs a start-up routine. It loads its settings, checks that the display and the other boards answer, and only then offers the cooking menu. E99.x means one of those start-up steps did not complete, and the manual names it a general initialization error. The x is a sub-number: the manual describes the whole group in one line, with one response, which is to unplug the appliance for about 10 seconds and restart. That power cycle gives every board a clean power-up and clears an interrupted start, for example when the supply flickered while the oven was booting. If the same error comes back, the problem is not a one-off. A board, a connector or the stored settings are not being read as they should, and the oven cannot go on to cook until the start-up routine passes. That kind of problem is beyond the keypad.
Affected models and control systems
The OES, OEB, OGS and OGB combi ovens (pre-C4). We used the translated English user manual for the line, which carries no revision or part number 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 followed by a digit shown soon after power-on
- Display starts and then stays on the message
- Oven will not offer a cooking menu
- Same code again after each restart
Possible causes
Likely causes — what usually sits behind error code E99.x on this control. A technician confirms which one it is before any part is replaced.
- Power flicker while the oven was starting up
- Loose display or control board connector
- Stored settings that the control cannot read at power-on
- Control board failing its own start-up check
Safe checks before calling for service
- Switch the oven off and unplug it from the outlet.
- Wait about 10 seconds, as the manual states.
- Plug the oven in and start it again, giving it time to finish its start-up.
- If an E99 code appears again, leave the oven off and contact customer service.
- Tell the technician the full code, including the digit after the dot, and whether the kitchen had a power interruption.
How a technician diagnoses error code E99.x
- Read the full E99.x code and history to see whether start-up stops at the same point every time.
- Check supply voltage and the breaker at the moment of power-up.
- Inspect the connectors between the display and control boards for looseness or corrosion.
- Check that the control loads its settings and identification data 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 carries line voltage and holds the oven's own configuration.
- Repeated power cycling can stress boards and hide the real cause, so testing has to be done in a controlled order.
- Restoring settings after a board change needs service tools and the exact model data.
How error code E99.x differs from similar codes
E96.0 reports a communications error while the oven is running, and E89.1 reports invalid data in the identification module. E99.x is the start-up check.
Technical reference
- Maker documentation
- Convotherm owner support
- Edition
- No revision/part number found in the text read
- Models / control
- Convotherm OES / OEB / OGS / OGB (older, pre-C4)
- Section
- Troubleshooting, Errors and required responses, pp. 161-162
- 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
What does the digit after E99 mean?
The manual describes E99.x as one general initialization error with one response, so treat every version the same way at first.
Is unplugging the oven safe?
It is the manual's own step. Wait about 10 seconds before plugging it back in.
Will E99.x clear if I wait?
Not usually. A restart after the unplug is the step to try, and a repeat needs service.
Need help with Convotherm error code E99.x?
A technician confirms the cause on site and gives you the price in writing before any work starts.