Alto-Shaam Combi Oven Error Code E15: Condenser Temperature High
E15 Condensor Temperature High means the condenser water at probe B3 stayed above 212 F (100 C) for more than 180 seconds. Press the Start icon to acknowledge it, and check that the oven's water supply is on. If it returns, a technician should check the cooling valve and the steam bypass hose.
Medium: the oven can try to resume, but it cannot cool its steam properly until the cause is fixed.
- Code
- E15
- 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 E15 mean?
Steam leaving the cavity is cooled in a condenser before it goes down the drain, and the oven does this by mixing in cold water through cooling solenoid Y2. Probe B3 reads the temperature of that condenser water. If B3 stays above 212 F (100 C) for more than 180 seconds, the control concludes the cooling is not working and posts E15 Condensor Temperature High, using the manual's spelling. The manual lists five causes. The water supply may be shut off, the steam bypass hose may be plugged, B3 may be wired wrong or failed, or Y2 may not open. Pressing Start acknowledges the message and the oven then tries to return to normal operation, but the same check is made the next time steam is vented. When it keeps appearing, the condenser water is usually either not arriving or not being measured correctly.
Affected models and control systems
Alto-Shaam Combitherm CT PROformance and CT Classic ovens, models 6-10, 10-10, 7-20, 10-20, 20-10 and 20-20 in electric and gas. The CT Express manual lists the same condition.
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
- E15 Condensor Temperature High on the display
- Hot water or steam coming from the drain
- Steam program ending early
Possible causes
Listed in Alto-Shaam's documentation
- Water supply shut off
- Plugged steam bypass hose
- B3 probe miswired
- B3 probe malfunction
- Cooling water solenoid Y2 malfunction
Other likely causes — what usually sits behind error code E15 on this control. A technician confirms which one it is before any part is replaced.
- Scale narrowing the passage inside the Y2 cooling valve in an area with hard water
- A water filter that is clogged and cutting flow to the cooling line while the fill line still works
Safe checks before calling for service
- Press the Start icon once to acknowledge E15.
- Check that the cold water valve to the oven is fully open and the hose has no kinks.
- Look at the floor drain for steam or very hot water leaving the oven.
- If E15 returns, note which program was running and call for service.
How a technician diagnoses error code E15
- Read the code and confirm cold water is reaching the oven at normal pressure.
- Test cooling solenoid Y2 for coil resistance and voltage when it should open.
- Check the steam bypass hose for blockage.
- Verify B3 wiring against the diagram and check the probe resistance against its chart.
- Replace Y2 or B3 only once the test shows which one failed.
- The cooling valve and probe circuit are inside the oven with live 208-240 V present.
- A plugged bypass hose is reached by pulling panels on a hot oven.
- Probe wiring must follow the oven's diagram exactly, because B3 can be miswired.
How error code E15 differs from similar codes
E25 and E40 concern the same probe B3 but report a failed or shorted sensor; E15 says the water the probe measures is too hot.
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
Why is it spelled Condensor?
That is how the manual and display print it; it means the condenser.
Can E15 be a bad probe rather than hot water?
Yes. B3 malfunction and B3 miswiring are two of the five listed causes.
Is E15 related to E25?
They share probe B3, but E25 means the probe is defective or disconnected.
Need help with Alto-Shaam error code E15?
A technician confirms the cause on site and gives you the price in writing before any work starts.