Convotherm Combi Oven Error Code E29.1-E29.4: Core Sensor Ground Fault
E29.1, E29.2, E29.3 and E29.4 on the older Convotherm OES, OEB, OGS and OGB ovens mean the core temperature sensor (CTS) has a ground fault. The manual's only response is to contact customer service. Time-based cooking is still possible.
Low: only core-probe cooking is lost.
- Code
- E29.1 / E29.2 / E29.3 / E29.4
- Maker
- Convotherm
- Equipment
- Combi ovens
- Applies to
- Convotherm OES / OEB / OGS / OGB (older, pre-C4)
What does Convotherm error code E29.1 / E29.2 / E29.3 / E29.4 mean?
The core temperature sensor is the probe pushed into the food, and its signal should only travel along its own wires. A ground fault means the signal has found another path to ground, for example because the cable insulation has been damaged by repeated bending, crushing in the door or heat from a tray. The control sees an impossible value, cannot use the probe, and shows one of E29.1 to E29.4. The number after the dot names the measuring point on the probe, but the manual gives all four the same meaning and the same response. A damaged probe does not affect cooking by time and temperature, so the oven can still be used that way. Core-probe programs have to wait until a technician has checked the probe, cable and socket.
Affected models and control systems
Older Convotherm combi ovens in the OES, OEB, OGS and OGB line, which came before the C4. The source is that line's English user manual, a translation of the original, with no revision number printed.
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
- E29.1, E29.2, E29.3 or E29.4 on the display
- Core-probe programs will not start
- Core temperature not shown or jumping
- Probe cable crushed, cut or burned
Possible causes
Likely causes — what usually sits behind error code E29.1 / E29.2 / E29.3 / E29.4 on this control. A technician confirms which one it is before any part is replaced.
- Probe cable insulation damaged by the door or a hot tray
- Moisture inside the probe plug
- Probe tip or body failed
- Socket contacts in the chamber wall wet or corroded
Safe checks before calling for service
- Unplug the probe and look along the cable for cuts, crushed spots or burn marks.
- Dry the plug and socket with a cloth if they are wet.
- Use time-based programs until the probe has been checked.
- Contact customer service as the manual instructs.
- Note which of the four codes appeared and how the probe has been stored.
How a technician diagnoses error code E29.1 / E29.2 / E29.3 / E29.4
- Read the code and history.
- Test the probe and cable separately for a path to ground.
- Inspect the socket and its wiring in the chamber wall.
- Check the probe input at the board.
- Replace the probe first.
- Replace the socket wiring if a new probe gives the same code.
- Socket wiring in the chamber wall is reached by removing panels near line-voltage parts.
- A replacement probe has to match the sensor type the oven expects.
- A ground path can be intermittent, which takes repeated testing.
How error code E29.1 / E29.2 / E29.3 / E29.4 differs from similar codes
E22.x reports the same probe with an open circuit, and E12.x reports it 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 keep cooking with E29.x?
Yes, by time and temperature. Only core-probe cooking is lost.
Could the door have damaged the cable?
A crushed or pinched cable is a common reason for a ground path, though the manual does not name a cause.
Do the four numbers mean different problems?
The manual treats them the same, so check the probe first.
Need help with Convotherm error code E29.1 / E29.2 / E29.3 / E29.4?
A technician confirms the cause on site and gives you the price in writing before any work starts.