Hobart Legacy+ Mixer Error OU1 / OU2 / OU3: Over Voltage
OU1, OU2 and OU3 appear on Hobart Legacy+ HL800 and HL1400 mixers when the motor drive sees a supply voltage that is too high. Stop the mixer, close the guard, and note whether the code came at start-up or when nearby equipment switched on. Cycle power once, and if an OU code returns, leave the mixer off and call us.
High: high voltage can damage the drive, and the mixer should stay off if the code returns.
What does Hobart error code OU1 / OU2 / OU3 mean?
The drive's electronics are rated for a range of supply voltage. When the incoming voltage runs above the top of that range, the drive stops the motor rather than let it reach its parts and shows OU1, OU2 or OU3 on the SmartTimer. The mixer will not run until power is cycled and the cause is corrected. The mixer itself may be fine while the building supply is the problem. High voltage can appear when a large load switches off and the line swings upward, when a transformer tap is set high, or when supply wiring in the building changed. The manual points to the incoming voltage at the mixer disconnect, measured with the mixer off and while loaded, whether other equipment on the same feed switches heavy loads at the moment of the code, the drive input terminals and wiring, and the drive itself once supply is ruled out. The display cannot tell a high building supply from a drive that reads wrong. The display text is OU1 / OU2 / OU3.
Affected models and control systems
Hobart Legacy+ HL800 and HL1400 mixers with the motor drive and SmartTimer display. The three numbers share one 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
- OU1, OU2 or OU3 on the SmartTimer display
- Code appearing when nearby equipment switches off or on
- Mixer will not run until power is cycled
Possible causes
Listed in Hobart's documentation
- Incoming voltage at the mixer disconnect above the drive's range
- Other equipment on the same feed switching heavy loads at the time
- Drive input terminals and wiring
- Drive itself, once supply is ruled out
Other likely causes — what usually sits behind error code OU1 / OU2 / OU3 on this control. A technician confirms which one it is before any part is replaced.
- A building transformer tap set high for a different load profile
- A large compressor on the feed that drops off and lets the line swing high
Safe checks before calling for service
- Stop the mixer and close the bowl guard.
- Note whether the code came at start-up or when nearby equipment switched on, and tell us.
- Cycle power to the mixer once.
- If an OU code returns, leave the mixer off and call us to schedule service, since high voltage can damage the drive.
- Tell us whether other equipment hesitated or ran louder at the same moment.
How a technician diagnoses error code OU1 / OU2 / OU3
- Read the code and ask which equipment switched at that moment.
- Measure supply voltage at the mixer disconnect, off and loaded.
- Log voltage over a period to catch swings when other loads switch.
- Inspect the drive input terminals and wiring for looseness or heat damage.
- Compare the drive reading with the measured supply.
- Replace the drive only if the supply is in range and OU persists.
- Measuring supply voltage means working on a live 208 to 240 V circuit.
- The display cannot tell a high building supply from a drive that reads wrong.
- Repeated high voltage can shorten the life of the drive and other equipment on the feed, so we measure the supply before we touch the mixer.
Technical reference
- Document
- Large Capacity Mixers Customer Maintenance Manual F48065 (10-22), Diagnostic Error Codes
- Maker documentation
- Hobart owner support
- Edition
- F48065
- Models / control
- Legacy+ HL800 / HL1400 motor drive + SmartTimer display
- Section
- Diagnostic Error Codes HL800 & HL1400, PDF pp. 9-11
- 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 Hobart mixer error codes
Is the mixer broken if OU shows?
Not necessarily. The building supply may be too high.
Why note when it happened?
A code at the moment other equipment switches off points at the supply.
Is OU the opposite of LU?
Yes. LU is too low a voltage; OU is too high.
Need help with Hobart error code OU1 / OU2 / OU3?
A technician confirms the cause on site and gives you the price in writing before any work starts.