Southbend EZ Com Oven Error Code Err CP:U: Controller RAM Check Failed
Err with CP:U on a Southbend EZ Com combination oven means the controller failed its on-board RAM check. The manual says the controller must be replaced. Turn the oven off and on once to see whether the code clears.
High: the controller failed an internal memory check and the oven cannot run reliably.
- Code
- Err + CP:U
- Maker
- Southbend
- Equipment
- Convection ovens
- Applies to
- Southbend EZ Com control
What does Southbend error code Err + CP:U mean?
On the EZ Com oven, Err appears in the TEMPERATURE display and the code appears in the TIME display, so the pair reads Err and CP:U. At power-up the controller runs a diagnostic, which takes between 35 and 105 seconds, and part of it is a check of its on-board RAM. If the check fails, CP:U appears. RAM is the memory the controller uses to hold the program and settings while it runs, so a failed check means the controller cannot be trusted to work. The manual says the controller must be replaced. For any error it adds that the cause should be fixed and the unit turned off and on to clear the code. Because the check runs only at power-up, the code often appears right when the oven is switched on and not in the middle of a cook.
Affected models and control systems
Southbend EZ Com combination ovens CG/12SC and CG/22SC.
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
- Err shows in the TEMPERATURE display and CP:U in the TIME display
- The oven shows the code after power-up
- The oven does not begin its normal operation
- The code returns on every start
Possible causes
Likely causes — what usually sits behind error code Err + CP:U on this control. A technician confirms which one it is before any part is replaced.
- Controller failed its on-board RAM check
- A supply disturbance that interrupted the controller's power-up check
- A controller board that has aged from heat and steam
Safe checks before calling for service
- Turn the oven off at the switch, wait a minute, and turn it on again.
- Wait up to two minutes for the power-up diagnostic to finish.
- Do not press keys during the diagnostic.
- If CP:U returns, write down the model and call us.
How a technician diagnoses error code Err + CP:U
- Read the code and confirm Err and CP:U on the displays.
- Check the supply and the connections to the controller.
- Power cycle and allow the full diagnostic.
- Verify the code repeats.
- Confirm the correct controller for the CG/12SC or CG/22SC.
- Replace the controller.
- The controller sits behind the panel with mains voltage and gas controls nearby.
- The diagnostic must be observed to the end.
- Controllers are matched to the model.
How error code Err + CP:U differs from similar codes
CP:U is a controller memory check at power-up, unlike bu:tn, FA:n, GA:S and Pr:0b, which name a button, a switch, gas and a probe.
Technical reference
- Maker documentation
- Southbend owner support
- Edition
- Part No. 1182851, Rev. 2
- Models / control
- Southbend EZ Com control
- Section
- Troubleshooting, Control panel error codes (manual p. 26; Gas Error flowchart p. 30)
- 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 Southbend convection oven error codes
Does CP:U mean a bad controller?
Yes. The manual says the controller failed its RAM check and must be replaced.
How long does the power-up diagnostic take?
Between 35 and 105 seconds.
Will resetting clear it?
Turning the oven off and on clears an error once its cause is fixed, but a failed RAM check stays until the controller is replaced.
Need help with Southbend error code Err + CP:U?
A technician confirms the cause on site and gives you the price in writing before any work starts.