Ultrafryer Commercial Fryer Error Code LO: Vat Temperature Too Low
LO on an UltraStat 23 display means the actual vat temperature is more than 10 degrees below the programmed vat temperature. The manual lists no cause or action, so start by checking whether the fryer is simply still heating or has just been loaded with cold product.
Medium: the fryer is cooking below its programmed temperature, which affects food quality and may mean it cannot heat.
- Code
- LO
- Maker
- Ultrafryer
- Equipment
- Fryers
- Applies to
- Ultrafryer UltraStat 23 controller (MEC-110 with enhanced SMS)
What does Ultrafryer error code LO mean?
The UltraStat 23 controller continually compares the temperature measured in the vat with the temperature programmed for the product. The manual's Display Descriptions page says LO is shown when the actual vat temperature is more than 10 degrees below the programmed value. In plain terms, the oil is noticeably colder than the control wants it. This is a description of a reading, not a numbered entry in an error table, and the manual has no troubleshooting steps for it. It can appear in ordinary use, such as right after a cold start or a large cold load of product, because the oil takes time to recover. It can also continue when the fryer cannot heat, and the manual does not separate those cases. The display shows exactly LO, and the controller keeps comparing the two temperatures, so the display should disappear once the vat is within 10 degrees of the setpoint again.
Affected models and control systems
This entry is from the Ultrafryer UltraStat 23 controller, the MEC-110 with enhanced SMS (10-product cooking controller). The manual is dated July 2009 and covers that controller only.
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
- LO showing on the display
- Oil temperature reading visibly below the programmed setpoint
- Product cooking slowly or coming out pale
Possible causes
Likely causes — what usually sits behind error code LO on this control. A technician confirms which one it is before any part is replaced.
- Fryer still heating up after a cold start or after a long idle period
- A large load of cold or frozen product pulled the oil temperature down
- Heating is not keeping up because a burner or element is not firing
- The temperature probe is reading lower than the real oil temperature
Safe checks before calling for service
- Look at the vat temperature on the display and compare it with the programmed setpoint.
- Wait a few minutes with no product in the vat and see whether the reading climbs toward the setpoint.
- If you just dropped a heavy load, reduce basket size and give the oil time to recover.
- If LO stays on with an empty, preheated vat, note the programmed temperature, the actual temperature shown, and how long it has been heating for the service call.
How a technician diagnoses error code LO
- Compare the controller reading with a calibrated thermometer in the oil to confirm whether the probe is accurate.
- Check the gas supply and shutoff on a gas fryer, or power and contactors on an electric one.
- Verify the heat call: confirm the control is calling for heat and the ignition or element circuit responds.
- Check the high-limit and any safety devices that might be keeping heat off.
- Test the temperature probe resistance against its specification.
- Replace the part that fails its test, then run a full heat-up and confirm LO clears at setpoint.
- Gas valve, ignition and burner checks involve live gas and wiring behind panels, which only a trained technician should open.
- Electric elements and contactors carry high voltage, and testing them means working on live circuits.
- Probe replacement and calibration require the controller's own settings and a reference thermometer in hot oil.
Technical reference
- Document
- UltraStat 23 Operating Instructions for the MEC-110 with Enhanced SMS, 10-Product Cooking Controller
- Edition
- 30A216 July 2009 (footer; 229-51339 Rev A, 2007 FAST)
- Models / control
- Ultrafryer UltraStat 23 controller (MEC-110 with enhanced SMS)
- Section
- Display Descriptions, printed p. 9 (images with descriptions); FILTER prompt on p. 7; no fault code table
- 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 Ultrafryer fryer error codes
Is LO an error?
The manual describes LO as a display condition: the oil is more than 10 degrees below the programmed temperature. It can be normal right after startup.
Can I keep cooking while LO is on?
Not well. Food cooked in oil that is too cold absorbs more oil and cooks unevenly, so wait for the display to clear.
What if LO never goes away?
If an empty vat will not reach setpoint after a normal preheat, the fryer is not heating properly and needs a technician.
Need help with Ultrafryer error code LO?
A technician confirms the cause on site and gives you the price in writing before any work starts.