Alto-Shaam Combi Oven Error Code E41: B4 Probe Shorted
E41 B4 Fault means probe B4, the steam generator temperature probe, is shorted to ground. Press the Start icon to acknowledge it, and have a technician check the probe and wiring before steam cooking.
Medium: the generator cannot be monitored until the probe circuit is repaired.
- Code
- E41
- Maker
- Alto-Shaam
- Equipment
- Combi ovens
- Applies to
- Combitherm CT PROformance (CTP) and CT Classic (CTC)
What does Alto-Shaam error code E41 mean?
Probe B4 reports the steam generator's temperature, and E13 depends on it. Here the control sees a different kind of problem. The probe circuit reads as a short to ground, which is a value no real temperature produces, so the control posts E41 B4 Fault. The manual's only cause is that the probe is miswired or has malfunctioned. The difference from E23 is useful: E23 is a B4 that cannot be read as an open, damaged or miswired probe, while E41 says the circuit is shorted to ground. Pressing Start acknowledges the message and the oven then tries to return to normal operation, but the short remains and steam programs cannot be protected by the temperature check. The generator runs hot in normal use, and heat damage to the lead insulation is one way a short can form next to the housing, which is why a technician looks at the lead path as well as the probe.
Affected models and control systems
Alto-Shaam Combitherm CT PROformance and CT Classic combi ovens in sizes 6-10, 10-10, 7-20, 10-20, 20-10 and 20-20, electric and gas, with steam generator probe B4.
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
- E41 B4 Fault on the display
- Steam programs unavailable or ending early
- No steam generator temperature shown
Possible causes
Listed in Alto-Shaam's documentation
- Probe B4 miswired or failed
Other likely causes — what usually sits behind error code E41 on this control. A technician confirms which one it is before any part is replaced.
- Heat-hardened lead insulation cracked where it touches the generator
- A wire pinched during an earlier service so the lead grounds against metal
Safe checks before calling for service
- Press the Start icon once to acknowledge E41.
- Do not run steam programs until the oven is checked.
- Let the oven cool before looking for steam or water leaks at the back.
- Tell the technician if descaling or other service was done recently.
How a technician diagnoses error code E41
- Read the code and check history for E13 and E23.
- Inspect the B4 probe and the lead route along the generator.
- Disconnect the probe and measure each lead to ground.
- Check the probe resistance against its chart.
- Repair the lead or replace B4 once the short is found.
- B4 sits on the steam generator, which stays hot after use.
- Testing leads to ground means isolating the circuit near live control wiring.
- The temperature check protects the generator from overheating.
How error code E41 differs from similar codes
E13 is a real high reading from B4, E23 an unreadable B4, and E41 B4 shorted to ground.
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)
- 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
How is E41 different from E23?
E23 means B4 is defective or miswired; E41 specifically says it is shorted to ground.
Can I run dry heat?
The oven tries to return to normal operation, but steam should wait for the repair.
Does descaling help?
Not for a short; it helps for E13.
Need help with Alto-Shaam error code E41?
A technician confirms the cause on site and gives you the price in writing before any work starts.