Wolf M Series Code 0B20: Upper Cooling Fan Triac Shorted Out

What 0B20 means

For Wolf M Series wall ovens such as the SO30TM and DO30PM and the newer SO3050 models, code 0B20 means the triac for the upper cooling fan is shorted, an alternate of 0B31. The cooling fan keeps the control area at a safe temperature, and its triac now cannot switch the motor off on command. Expect 0B20 on the display, and possibly a fan that keeps running after cooking ends.

Common causes of 0B20

Shorted triac on the upper cooling fan
Board output failing closed
Power surge that harmed the switching circuit

✓ One safe check you can try

1. Press off, and keep clear of the oven while it cools. 2. At the panel, cut power to the oven for a minute and bring it back. 3. Try the oven briefly, keeping an eye out for 0B20. 4. If 0B20 returns, leave the oven off and call us.

! Why to stop there

A switch that has failed closed lives on the board behind live wiring, out of reach of a safe home check.
Uncontrolled airflow may upset baking results and heat the control area unevenly.
We give you the cost in writing before starting.

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.

→Same appliance

Other Wall Oven codes

0121Wolf M Series Oven Code 0121: upper right convection relay shorted 0221Wolf M Series Code 0221: Upper Bake Element DLB Shorted 0321Wolf M Series Oven Code 0321: Broil Relay Shorted on the Upper Element 0421Wolf M Series Code 0421: upper left convection relay shorted 0630Wolf M Series Oven Code 0630: Auxiliary DLB Shorted 2420Wolf M Series Code 2420: Relay board RTD circuit 3C20Wolf M Series Code 3C20: High input voltage 2631Wolf M Series Code 2631: Relay board door switch circuit

0B200B20 questions

How serious is 0B20?

It points to a shorted triac on the upper cooling fan, also reported as 0B31 on certain models. It is not an emergency, but the fan is no longer under proper control.

What will I notice with 0B20?

Mostly a fan that runs when it should not, or an oven that cools and heats a little unevenly. Some owners notice nothing beyond the code.

Does a reset fix 0B20?

Only if the short was a one-time event. When 0B20 keeps returning, we confirm it on site and give a written price before any repair.