True Refrigerator Error Code P1: Dixell Thermostat Probe Failure
P1 on a True cabinet with a Dixell controller means the control has lost the signal from its thermostat probe, the sensor that reports cabinet air temperature. Silence the alarm, check the door and power, and measure food temperature. If P1 stays on, move perishable product to another cooler and call us.
Medium: the control is blind to cabinet air, so temperature can drift either way.
- Code
- P1
- Maker
- True
- Equipment
- Reach-in refrigerators
- Applies to
- Dixell controller
What does True error code P1 mean?
P1 means the control has lost the signal from its thermostat probe. The same controller turns up in True reach-in refrigerators such as the T-23-HC and T-49-HC, and in the freezers, prep tables, display merchandisers and back bar coolers built on the same platform. The control uses that probe to decide when to run the compressor. Without a reading it cannot judge, so the box may run warm, run cold, or cycle oddly. Whether it is the probe, the wiring or the input, the result is the same: the control is blind to the cabinet air. A technician checks the probe wiring and connector at the control, tests the probe against a resistance chart, looks for leads pinched near the door frame or fan shroud, and checks the input on the board last.
Affected models and control systems
True cabinets with a Dixell controller, including the T-23-HC and T-49-HC, plus freezers, prep tables, merchandisers and back bar coolers on the same platform.
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
- P1 on the display
- Alarm tone
- Cabinet running too warm or too cold
- Compressor cycling in an odd pattern
Possible causes
Listed in True's documentation
- The thermostat probe wiring and its connector at the control
- The probe itself, which can be checked against a resistance chart
- The probe input on the control board
- Probe leads pinched near the door frame or fan shroud
Other likely causes — what usually sits behind error code P1 on this control. A technician confirms which one it is before any part is replaced.
- A probe lead chewed through by a fan blade
- Ice around the probe tip
- A connector corroded after washdowns
Safe checks before calling for service
- Press any button to silence the alarm.
- Check that the cabinet door is shut and the unit has power.
- Look at the product temperature with a thermometer so you know whether food is still safe.
- If P1 stays on the display, move perishable product to another cooler.
- Call us and tell us the cabinet model.
How a technician diagnoses error code P1
- Read the code and confirm cabinet temperature.
- Inspect the probe, lead and connector at the control.
- Measure probe resistance and compare with the resistance chart.
- Check the lead path at the door frame and fan shroud for pinches.
- Test the probe input at the board.
- Replace the probe, then the board only if the input fails.
- The probe plugs into a control board beside powered wiring.
- Testing a probe needs a meter and a chart for its temperature.
- Without a probe the compressor can run continuously or not at all, risking food.
How error code P1 differs from similar codes
On LAE controls the thermostat probe failure is shown as E1, and on Carel as E0.
Technical reference
- Document
- Commercial Refrigeration General Control Guide TEC_TM_001 Rev C, Dixell p.96 Display Code Definitions
- Edition
- TEC_TM_001 | REV. C | EN, 09/3/2025, P#811072
- Models / control
- Dixell controller
- Section
- Electronic Control (with Display) - Display Code Definitions: Carel p. 74, Danfoss ERC/ETC p. 87, Dixell p. 96, LAE p. 110
- 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 True reach-in refrigerator error codes
What is the P1 probe?
The thermostat probe, which reports cabinet air temperature to the control.
Is the food at risk?
Check with a thermometer. The control may run too warm or too cold without the probe.
Is P1 the same as E1 on another True?
They describe the same type of problem on different controls, but the diagnosis follows the control brand.
Need help with True error code P1?
A technician confirms the cause on site and gives you the price in writing before any work starts.