Alto-Shaam Combi Oven Error Code E24: B5 Bypass Probe Failure
E24 B5 Bypass Probe Fault means the bypass steam temperature probe, B5, is defective or disconnected. Press the Start icon to acknowledge it, and ask a technician to check B5 and its wiring.
Medium: steam handling is affected but the manual shows the oven can try to resume.
- Code
- E24
- Maker
- Alto-Shaam
- Equipment
- Combi ovens
- Applies to
- Combitherm CT PROformance (CTP) and CT Classic (CTC); Combitherm CT Express / ESi / CCi (older 4-10 and 4.10 units; boiler or generator electric/gas)
What does Alto-Shaam error code E24 mean?
The bypass is the route steam takes from the cavity to the condenser, and probe B5 measures the temperature of steam in that path. The control uses it with other probes to know steam is leaving the oven as it should. If B5 gives a reading that is open, shorted or otherwise impossible, the control posts E24 B5 Bypass Probe Fault. The manual lists two causes: the B5 probe has failed, or it is miswired. After Start is pressed the oven tries to carry on, but the condition repeats at the next steam cycle if the probe cannot be read. This is a sensor circuit code, so it says nothing about whether the bypass hose is plugged; that is a cause for E15 and E36. It is also separate from E25, the condenser probe B3, which is a different sensor on a nearby circuit.
Affected models and control systems
Electric and gas CT PROformance and CT Classic combi ovens in sizes from 6-10 up to 20-20. E24 is also found in the CT Express list.
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
- E24 B5 Bypass Probe Fault on the display
- Steam cycles ending or not starting
- Normal dry cooking continuing in some cases
Possible causes
Listed in Alto-Shaam's documentation
- B5 probe malfunction
- B5 probe miswired
Other likely causes — what usually sits behind error code E24 on this control. A technician confirms which one it is before any part is replaced.
- A probe lead damaged where it runs close to the hot bypass hose
- Connector corrosion from steam condensing near the probe
Safe checks before calling for service
- Press the Start icon once to acknowledge E24.
- Check for signs of steam leaking around the back of the oven.
- Let the oven cool before any inspection of the outside of the venting area.
- If E24 returns, record which program was running and whether E25 or E15 also showed.
How a technician diagnoses error code E24
- Read the code and check whether E25 or E15 also appear.
- Inspect B5 and its leads along the bypass path, with the oven cool.
- Compare the wiring against the diagram for miswiring after previous repairs.
- Measure B5 resistance and compare with the chart.
- Replace B5 only when the circuit tests show the probe has failed.
- B5 sits in the hot steam path and its leads run toward live control wiring.
- Distinguishing an open probe from a bad connection takes a meter.
- Probe replacement needs the oven's panels removed after it cools.
How error code E24 differs from similar codes
E25 concerns the condenser probe B3 and E24 the bypass probe B5; E15 and E36 are bypass hose or water causes, not probe circuit errors.
Technical reference
- Maker documentation
- Alto-Shaam owner support
- Edition
- MN-35949 Rev 08 03/22
- Models / control
- Combitherm CT PROformance (CTP) and CT Classic (CTC); Combitherm CT Express / ESi / CCi (older 4-10 and 4.10 units; boiler or generator electric/gas)
- Section
- Error Codes, pp. 25-31
- 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 Alto-Shaam combi oven error codes
Where is B5?
It measures steam temperature in the bypass; the manual does not give more detail than that.
Is E24 the same as E25?
No, E25 is condenser probe B3.
Will E24 stop the oven?
The oven tries to return to normal operation after Start, but steam functions may not run properly.
Need help with Alto-Shaam error code E24?
A technician confirms the cause on site and gives you the price in writing before any work starts.