Wolf CSO Steam Oven Code U1: L2 supply problem

What U1 means

U1 on Wolf convection steam ovens equals error E58, a power-supply reading on the L2 line. On knob-control CSO24 ovens it means no signal on L2: no conductor on the L2 clamp, or a tripped breaker or fuse. On touch-control CSO30, CSO2450 and CSO3050 ovens, E58 is L2 above 280 VAC for 3 seconds. The oven will not run and shows U1.

Common causes of U1

Breaker or fuse tripped on one leg
No conductor on the L2 clamp (knob control)
L2 voltage above 280 VAC for 3 seconds (touch control)

✓ One safe check you can try

1. Find the oven's double-pole breaker and look for a tripped handle. 2. Switch it fully off, wait one minute, then on. 3. Check whether the oven's display lights again. 4. If U1 returns, keep the breaker off and book a visit; do not open any panels.

! Why to stop there

The knob-control and touch-control meanings differ, so the fix depends on the model and a live reading.
Wiring at the clamp and panel is for licensed hands only.
A written price arrives first, and our repair has a 30-day workmanship warranty.

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

E42Wolf Convection Steam Oven Code E42: Water temperature sensor error E87Wolf 24-Inch E Series Code E87: Exhaust slide valve jammed or shorted E87Wolf Convection Steam Oven Code E87: Exhaust slide valve stuck 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

U1U1 questions

Why does a tripped breaker show up as U1?

On knob-control ovens, E58 means no signal on L2, and a tripped breaker or fuse on that leg is listed. The oven sees only one supply leg and refuses to run.

Does U1 mean the same on touch-control models?

No. On touch-control ovens it is L2 above 280 VAC for 3 seconds, an overvoltage reading. We check your model before deciding which test applies.

Can I tighten the wire at the clamp myself?

Please do not. Work at the terminal block involves live supply lines. A technician will test the voltage and tighten or correct the connection safely.