Alto-Shaam Combi Oven Error Code E34: Drain Pump Failure
E34 Steam Generator Drain Pump Fault means the water level did not fall below the lower level probe within 3 minutes while the drain pump ran in the cleaning program. Press the Start icon to acknowledge it, and have the pump and level probe checked.
Medium: cleaning cannot finish, but ordinary cooking is not named as affected.
- Code
- E34
- 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 E34 mean?
During the cleaning program the oven empties the steam generator with its drain pump. The control starts the pump and watches the lower level probe, expecting the water to drop below it. If the water is still touching that probe after 3 minutes, the control posts E34 Steam Generator Drain Pump Fault. The manual lists three causes. Calcium build-up or a blockage in the pump slows or stops it, the pump itself has failed, or the water level probe has failed and still reads wet when the generator is empty. Pressing Start acknowledges the message and the oven then tries to return to normal operation, but the next cleaning run repeats the same draining test. Because it appears during cleaning, it often shows up in kitchens with hard water, where scale builds up between descales. The code concerns draining; low water at fill time is E01.
Affected models and control systems
CT PROformance and CT Classic ovens, 6-10 through 20-20, electric and gas, during their cleaning program. The CT Express manual lists E34 with the same meaning.
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
- E34 Steam Generator Drain Pump Fault on the display
- Cleaning program ending early
- Water standing in the generator after a cleaning cycle
Possible causes
Listed in Alto-Shaam's documentation
- Calcium build-up or blockage in the drain pump
- Drain pump malfunction
- Water level probe malfunction
Other likely causes — what usually sits behind error code E34 on this control. A technician confirms which one it is before any part is replaced.
- A drain line downstream of the pump kinked or blocked so the pump cannot push water out
- A level probe coated with scale so it reads wet after the water has gone
Safe checks before calling for service
- Press the Start icon once to acknowledge E34.
- Check that the oven's floor drain is clear and not backing up.
- Skip the cleaning program for now, and note that E34 appeared during it.
- Tell the technician when the generator was last descaled and whether the kitchen uses a water filter.
How a technician diagnoses error code E34
- Read the code and confirm it appeared during the cleaning program.
- Check the drain line and standpipe for a blockage beyond the oven.
- Inspect the drain pump for scale and run it to see whether it moves water.
- Meter the pump motor and the level probe circuit.
- Descale or replace the pump or probe depending on what the test shows.
- The generator holds hot water and the pump circuit carries live 208-240 V.
- Descaling involves acid cleaners and requires the generator to be drained safely.
- Telling a scaled probe from a failing pump needs a meter and watching the level.
How error code E34 differs from similar codes
E01 is low water at fill time, E34 is water failing to drain in cleaning, and E36 involves cavity temperature in steam programs.
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
Does E34 mean the pump is dead?
Not necessarily. Scale or a blocked line is the first listed cause.
Can I still cook?
The oven tries to return to normal operation, but you should avoid the cleaning program until it is repaired.
Why only during cleaning?
That is when the control makes the generator drain and checks the lower level probe.
Need help with Alto-Shaam error code E34?
A technician confirms the cause on site and gives you the price in writing before any work starts.