Alto-Shaam Combi Oven Error Code E43: N6 Cavity Probe Shorted
E43 N6 Fault means the cavity probe, N6, is shorted to ground. Press the Start icon to acknowledge it, and stop cooking until a technician checks the probe and wiring.
High: heating control depends on N6, so the oven should not be used until it is repaired.
- Code
- E43
- Maker
- Alto-Shaam
- Equipment
- Combi ovens
- Applies to
- Combitherm CT PROformance (CTP) and CT Classic (CTC)
What does Alto-Shaam error code E43 mean?
The cavity probe N6 is the oven's main temperature sensor, so every convection, combination and steam program depends on it. When the control sees the probe circuit shorted to ground, it cannot trust any temperature value and posts E43 N6 Fault. The manual's single cause is a probe that is miswired or has malfunctioned. This differs from E21, where N6 is defective or disconnected, and from E11 and E36, where N6 reads too hot. A short is a wiring-level problem that could come from a damaged lead or a probe that has failed. Pressing Start acknowledges the message and the oven then tries to return to normal operation, but a heating oven should not run on a cavity probe that cannot be read correctly. The risk is overheating, because the control relies on N6 to know when to stop heating.
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 cavity probe N6.
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
- E43 N6 Fault on the display
- Oven not heating or stopping at start-up
- Cavity temperature missing or wrong on the display
Possible causes
Listed in Alto-Shaam's documentation
- Probe N6 miswired or failed
Other likely causes — what usually sits behind error code E43 on this control. A technician confirms which one it is before any part is replaced.
- A lead scorched against the cavity wall where it runs near the heating element
- Spray from high-pressure cleaning reaching the probe connector
Safe checks before calling for service
- Press the Start icon once to acknowledge E43.
- Turn the oven off and let it cool.
- Avoid cooking with the oven until it is checked.
- Report whether the oven was washed or moved before E43 appeared.
How a technician diagnoses error code E43
- Read the code and check history for E21, E11 and E36.
- Inspect the N6 probe and its harness with the oven cool.
- Disconnect N6 and measure resistance from each lead to ground.
- Compare with the probe chart at room temperature.
- Replace N6 or repair its wiring once the short is located.
- N6 is the sensor that keeps heating in check, so a wrong reading can overheat the cavity.
- Wiring tests happen next to the live element circuit.
- Probe replacement depends on correct routing of the harness.
How error code E43 differs from similar codes
E21 is N6 defective or disconnected, E11 is N6 reading above 600 F (315 C), and E43 is N6 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
Is it safe to keep cooking after E43?
No. The oven relies on N6 to control heat.
Can high-pressure cleaning cause E43?
Water in the connector is a plausible path to a short, though the manual lists only a miswired or failed probe.
Is E43 the same as E21?
No. E21 is a defective or disconnected N6; E43 is a short.
Need help with Alto-Shaam error code E43?
A technician confirms the cause on site and gives you the price in writing before any work starts.