UE • Mitsubishi Electric
Fault Code UE Mitsubishi Electric: Causes, Diagnosis and Solution
Fault code UE indicates abnormal pressure detected by the pressure sensor (63HS) when it registers 0.1 MPa or less. Detection is inactive for 3 minutes after compressor start and during or after defrost.
Proof status : Manufacturer reference needed for the exact range
Source: Mitsubishi Electric documentation (service manual – according to product reference)
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Founder of AskMarcel.app. Sheets are written from manufacturer documentation; the reference is shown when it has been verified.
In brief
Fault code UE on Mitsubishi Electric means: Fault code UE indicates abnormal pressure detected by the pressure sensor (63HS) when it registers 0.1 MPa or less. Detection is inactive for 3 minutes after compressor start and during or after defrost. Most common cause: The main cause is a failure of the pressure sensor (63HS), a disconnection or break in the sensor wire on the outdoor controller board, or a failure of the outdoor controller board itself. First action: Check the connection of the connector (63HS) on the outdoor controller board.. Call a registered engineer if the fault returns after basic checks or involves refrigerant work (F-Gas registered engineer required).
According to the Ecodan PUHZ HW140VHA2 BS Service Manual OCH439N, the UE code triggers when the 63HS pressure sensor reads 0.1 MPa or less, with detection disabled for 3 minutes after compressor start.
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What does fault code UE on Mitsubishi Electric mean?
Fault code UE indicates abnormal pressure detected by the pressure sensor (63HS) when it registers 0.1 MPa or less. Detection is inactive for 3 minutes after compressor start and during or after defrost.
The main cause is a failure of the pressure sensor (63HS), a disconnection or break in the sensor wire on the outdoor controller board, or a failure of the outdoor controller board itself.
Symptoms
- Display of fault code UE on the outdoor unit.
- Fault code UE flashes 14 times or more with a 2.5-second pause (according to Extract 3).
- Unit stops operating to protect the system.
- Detection of pressure at or below 0.1 MPa by the microprocessor.
Diagnosis
1. Check Sensor Connection
- Check the connection of the connector (63HS) on the outdoor controller board.
- Check for a break in the thermocouple sensor wire (63HS).
2. Check Pressure via Microprocessor
- Check the pressure via the microprocessor using the pressure sensor (63HS).
- Refer to the outdoor unit monitoring function (SW2) in the manual.
3. Replace Controller Board
- If connections and sensor are valid, replace the outdoor controller board.
- Check if the error persists after replacement.
Repair and return to service — Mitsubishi Electric fault UE
Start by checking the connection of the connector (63HS) on the outdoor controller board and inspect the sensor wire for any breaks. If the connection is correct, check the pressure measured by the microprocessor. If the sensor is faulty or the controller board is the cause, replace the outdoor controller board.
When should you call an F-Gas engineer?
Contact an F-Gas registered engineer if the fault returns after basic checks, involves refrigerant charging, or requires PCB or compressor replacement on Mitsubishi Electric.
Affected models
- Ecodan PUHZ HW140VHA2 BS
- Ecodan PUHZ HW140YHA2 BS
- Ecodan ATW PUHZ W50VHA BS
- Ecodan PUHZ SW50VKA BS
- MUYTP3550VFS
- Ecodan PUHZ HW140 and W50 series ranges
Field context
This code appears during a low pressure anomaly detected by the outdoor unit monitoring system. It is crucial to distinguish this error from other codes such as the UE code related to closed valve detection (Extract 3), as the diagnostic procedure for pressure involves checking the sensor and wiring.
Frequently asked questions
Why does code UE not trigger immediately after start-up?
Detection of the pressure anomaly (sensor 63HS < 0.1 MPa) is intentionally inactive for 3 minutes after compressor start, as well as during and after the defrost cycle. This delay prevents false triggers due to transient pressure fluctuations during these specific operational phases, ensuring the code only appears if the condition persists.
What is the first diagnostic step for a UE code?
The first step is to check the physical connection of the 63HS connector on the outdoor controller board and inspect the sensor wire for any breaks. It is essential to ensure good contact before proceeding with electrical or pressure measurements via the microprocessor, as a simple disconnection or wire break can be the root cause of the pressure reading.
How do you differentiate the pressure UE code from the closed valve UE code?
Although the displayed code is identical (UE), the manuals distinguish the causes. The pressure-related code (Extract 3 mentions another UE condition) specifically concerns the 63HS sensor detecting < 0.1 MPa. In contrast, the UE code for a closed valve is triggered by compressor current detection indicating a closed stop valve (flashing 14 times or more). Diagnosis for the pressure code involves checking the sensor and wiring, while the valve code requires checking the stop valves.
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