Convotherm Combi Oven Error Code E04.0: Secondary Fan
E04.0 on the older Convotherm OES, OEB, OGS and OGB ovens means a problem with the secondary fan in the electrical compartment. Clean the fluff filter, clear the air intake in the base, and if the code stays, contact customer service.
Medium: the oven may stop to protect its electronics, and cleaning is the first step.
- Code
- E04.0
- Maker
- Convotherm
- Equipment
- Combi ovens
- Applies to
- Convotherm OES / OEB / OGS / OGB (older, pre-C4)
What does Convotherm error code E04.0 mean?
Besides the main fan in the cooking chamber, these ovens have a secondary fan that cools the electrical compartment. The control checks that fan, and when it slows, stops or cannot move enough air, it shows E04.0. The manual's text is short: it names the secondary fan in the electrical compartment. Its steps are the same as for the overheating message next to it: clean the fluff filter, clear the air intake in the base, and then contact customer service. Those steps matter because a fan fed with lint-laden or blocked air works harder, and the filter is the cheapest protection the electronics have. If the fan itself is worn or its wiring has failed, the filter cleaning will not change anything and the oven needs a technician.
Affected models and control systems
Convotherm OES, OEB, OGS and OGB, the combi ovens that preceded the C4. The code comes from the line's translated user manual, and no edition number is shown in it.
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
- E04.0 on the display
- Cooling fan under the oven louder, slower or silent
- Oven stops heating
- Heavy lint in the fluff filter
Possible causes
Likely causes — what usually sits behind error code E04.0 on this control. A technician confirms which one it is before any part is replaced.
- Fan blades clogged with lint and grease
- Fan bearing worn so the motor runs slow
- Loose connector at the fan
- Intake in the base blocked
Safe checks before calling for service
- Turn the oven off.
- Clean the fluff filter on the oven floor.
- Clear the air intake in the base of the appliance.
- Restart the oven and listen for the cooling fan.
- If E04.0 stays, contact customer service and say whether the fan runs at all.
How a technician diagnoses error code E04.0
- Read E04.0 and the history.
- Check airflow through the filter and intake.
- Check the fan for rotation, noise and free movement of the blades.
- Measure the supply voltage at the fan connector when the oven is on.
- Look at the compartment temperature while the fan runs.
- Replace the fan once the supply is confirmed good.
- The fan sits in the electrical compartment next to boards and line-voltage wiring.
- Voltage at the fan is read with the oven powered, which an operator cannot do safely.
- A seized fan can lead to overheated boards, so we check the electronics when we replace it.
How error code E04.0 differs from similar codes
E02.0 reports the compartment as too hot, while E04.0 reports the secondary fan itself. Both begin with the filter and intake.
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
Is E04.0 the same as E02.0?
No. E02.0 says the compartment is too hot; E04.0 says the secondary fan has a problem.
Why clean the filter for a fan code?
The manual lists it first, since lint load makes the fan work harder.
Can I use the oven if the fan is loud but E04.0 is gone?
A loud fan is worth mentioning to service before it stops.
Need help with Convotherm error code E04.0?
A technician confirms the cause on site and gives you the price in writing before any work starts.