Convotherm Combi Oven Error Code E23.0: Steam Sensor Open Circuit
E23.0 on the older Convotherm OES, OEB, OGS and OGB ovens means the steam generator sensor (B4) has an open circuit. The manual's only response is to contact customer service. Steam stays off until it is repaired.
Medium: steam is off, but dry cooking continues.
- Code
- E23.0
- Maker
- Convotherm
- Equipment
- Combi ovens
- Applies to
- Convotherm OES / OEB / OGS / OGB (older, pre-C4)
What does Convotherm error code E23.0 mean?
Sensor B4 watches the temperature of the steam generator, the small boiler that makes steam. The control reads it through a small circuit, and an open circuit means that circuit is broken. A wire near the hot generator may have become brittle, a plug may have worked loose, or the sensor may have failed. With no signal, the control cannot tell whether the generator is safe to heat, so it stops steam and shows E23.0. The oven can still cook with dry heat, but steam and combi programs are off. The manual says to contact customer service. The wire and plug are near hot metal and water, and testing them means getting to the generator, which is not an operator job. Because the B4 wire runs close to the hottest part of the oven, repeated heating and cooling is a common way for a connection there to work loose over the years. The control reports the problem the same way whether the wire is cracked or the plug is only dirty, so a technician has to measure rather than guess.
Affected models and control systems
Convotherm OES, OEB, OGS and OGB combi ovens (the older, pre-C4 line), from that line's user manual, an English translation of the original edition. It does not state a revision number.
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
- E23.0 on the display
- Steam programs will not start
- Dry heat still works
- Message right after start-up or on a steam request
- Steam output missing even though the water supply is on
Possible causes
Likely causes — what usually sits behind error code E23.0 on this control. A technician confirms which one it is before any part is replaced.
- Wire to the B4 sensor brittle or broken near the generator
- Plug loose at the connector
- Sensor failed open
- Connector corroded by moisture
Safe checks before calling for service
- Switch the oven off and let the steam generator cool.
- Leave the steam generator drain and rinse settings as they are; changing them will not clear a sensor circuit code.
- Restart and try a dry-heat program.
- Contact customer service as the manual instructs.
- Note whether steam ever worked after the last restart.
How a technician diagnoses error code E23.0
- Read E23.0 and the history.
- Measure B4 resistance at the sensor.
- Check continuity of the cable and plug.
- Inspect the board input for B4.
- Replace the sensor or cable as the tests show.
- Run a steam test.
- The generator and its sensor sit in a hot, wet zone.
- The circuit is tested with a meter near line-voltage parts.
- Replacing a sensor on the generator means draining it first and refilling it, so the work is plumbing as well as electrical.
How error code E23.0 differs from similar codes
E23.1 is the same sensor with a ground fault; E13.0 is the generator sensor reading too high.
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
Can I cook without steam?
Yes, with dry heat, while E23.0 is on.
What does B4 mean?
The manual labels the steam generator sensor B4 for this code.
Why does dry heat still work?
The dry-heat functions do not rely on the steam generator sensor, so the control lets them continue while steam is held off. Steam and combi programs wait for the repair.
Need help with Convotherm error code E23.0?
A technician confirms the cause on site and gives you the price in writing before any work starts.