Wolf CSO Steam Oven Code U2: mains undervoltage

What U2 means

On Wolf convection steam ovens (CSO24 knob control, CSO30, CSO2450 and CSO3050 touch control), U2 is error E61 and U3 is error E62. Both describe undervoltage in the mains supply, or a mains calibration error. The oven is not receiving the line voltage it expects, so it will not start a cycle. You see U2 on the display, or U3 when the other reading is active.

Common causes of U2

Supply voltage dropping below the required level
Mains calibration error (E62)
Loose or undersized supply connection
Heavy load sharing the same circuit

✓ One safe check you can try

1. Switch off any big appliances running on the same circuit. 2. Turn the oven's breaker off for one minute, then on again. 3. Check whether lights elsewhere in the home dim when the oven starts. 4. If U2 returns, leave the oven off and call us or an electrician.

! Why to stop there

Low voltage needs a live meter reading to confirm, which is not an owner task.
The cause may be in the supply and not the oven, so we test both ends.
We quote in writing first, with a 30-day workmanship warranty on our repair.

Opening a panel yourself does not automatically cancel a manufacturer warranty, but it can cause accidental damage, and some manufacturers set their own service conditions. Check your warranty terms, or ask us, before deciding.

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Other Steam Oven codes

E26Wolf 24-inch E Series Code E26: Break or loose contact in climate sensor, or blocked duct F0Wolf Convection Steam Oven Code F0: Core temperature probe sensor problem F6Wolf Convection Steam Oven Code F6: Processor and Main Relay Error E51 F1Wolf Convection Steam Oven Code F1: Food probe error F15Wolf CSO Steam Oven Code F15: niche running too hot F10Wolf Convection Steam Oven Code F10: Control moisture or water tank valve F17Wolf CSO Steam Oven Code F17: climate sensor overtemperature F13Wolf Convection Steam Oven Code F13: Cabinet opening too hot

U2U2 questions

What do U2 and U3 mean?

U2 is E61 and U3 is E62. Both point to undervoltage in the mains supply or a mains calibration error. The oven shuts down because the voltage is not what the electronics expect.

Could my house wiring cause U2?

Yes. A loose connection, a tired breaker or a heavy shared load can all lower the voltage the oven sees. We test at the oven first, and an electrician may be needed for the panel.

Will the oven recover after a power dip?

If the dip was brief, a breaker reset may clear it. If U2 or U3 returns, the low-voltage condition is ongoing and should be traced before more cycles are run.