Mitsubishi Heavy Industries Aircon E42
Capture the Mitsubishi Heavy Industries E42 fault correctly, then see what should be checked before parts are quoted. Match the model first; same-looking signals can point to different rows.
What does Mitsubishi Heavy Industries E42 mean?
Mitsubishi Heavy Industries E42 is listed as current cut and current-cut or compressor-overcurrent protection in Inverter Split, Multi-Split, Single-Split rows such as Singapore Rocket YYS single split, SRK-YYS indoor with SRC-YYS outdoor. This meaning comes from the manufacturer's own diagnostic material. Do not collapse this code across model families; use the model, series, or system type to choose the right row. Confirm the exact model, series, or signal row before accepting a parts quote.
Choose the listing that matches your unit
The same code has more than one listed meaning. Match the model family, the system type and the unit that shows the code before approving parts.
| Code | What it means | What to check first |
|---|---|---|
| Singapore Rocket YYS single split / MHI Service Support Handbook RAC RUN/TIMER checklist / Inverter PAC FDC outdoor diagnostics | Current cut | Match this meaning to your installed model and the unit that shows the code, then use the checks below. |
| Inverter PAC SRC outdoor diagnostics | Compressor current cut or closed service valve | Confirm the installed unit belongs to Inverter PAC SRC ZHX-S / ZIX-S / ZJX-S / ZMX-S / ZSX-S outdoor units before using this meaning. |
| Inverter KX VRF diagnostics | Current-cut or compressor-overcurrent protection | Confirm the installed unit belongs to Inverter KX KX4 / KX6 / KXRE6 / KXZE1 / KXZPE1 / KXZRE1 systems before using this meaning. |
- Code
- Singapore Rocket YYS single split / MHI Service Support Handbook RAC RUN/TIMER checklist / Inverter PAC FDC outdoor diagnostics
- What it means
- Current cut
- What to check first
- Match this meaning to your installed model and the unit that shows the code, then use the checks below.
- Code
- Inverter PAC SRC outdoor diagnostics
- What it means
- Compressor current cut or closed service valve
- What to check first
- Confirm the installed unit belongs to Inverter PAC SRC ZHX-S / ZIX-S / ZJX-S / ZMX-S / ZSX-S outdoor units before using this meaning.
- Code
- Inverter KX VRF diagnostics
- What it means
- Current-cut or compressor-overcurrent protection
- What to check first
- Confirm the installed unit belongs to Inverter KX KX4 / KX6 / KXRE6 / KXZE1 / KXZPE1 / KXZRE1 systems before using this meaning.
What to do now
Use these steps before customer action, gas work, a pressure check, or parts quote.
Stop using the unit if E42 returns
Stop using the unit if E42 returns with weak cooling, frost, hissing, or outdoor-unit tripping.
No manufacturer reset steps listed for E42
Capture the complete E42 pattern and model stickers first. The manufacturer lists no customer reset procedure; do not treat a generic power-cycle as manufacturer guidance.
Send these to us
E42 error code and blinking light, a clear display photo and blinking-light video if the unit shows one, Mitsubishi Heavy Industries model stickers, affected rooms, operating state when the code appeared, and cooling-loss timeline and any recent gas top-up
Guidance for your model
Notes that match the code to your exact model. Electrical, refrigerant, wiring, resistance and component checks are for a technician.
| Detail | What it says |
|---|---|
| Diagnostic note | Record the exact E-code and whether it came from the indoor display, wired remote, or outdoor PCB, then arrange diagnosis by a qualified Mitsubishi Heavy Industries technician. |
| Diagnostic note | Record the exact RUN/TIMER blink pattern, optional wired-remote E-code, and whether the outdoor indicator is flashing before arranging diagnosis. |
| Diagnostic note | Stop repeated reset attempts. Isolate the system and have a qualified technician check supply voltage, inverter components, compressor wiring, and compressor condition. |
| Singapore / model note | Singapore Rocket YYS model family is from the Mitsubishi Heavy Industries Aircon Singapore residential page and RAC catalogue. Fault rows are from the official MHI RAC single-split indication table; no exact public Singapore YYS fault manual was found. |
| Singapore / model note | MHI Service Support Handbook pages 16-18 RAC indication table. This is a broad residential RAC cross-check, not a model-specific operation manual; non-residential handbook sections are excluded. Checklist cause: Compressor locking, open phase on compressor output, short circuit on power transistor, or closed service valve. |
| Singapore / model note | Official current MHI commercial error-table row E42. PAC/KX family applicability and display detail are cross-checked against MHI Service Support Handbook PDF pages 31, 32, 38. Confirm the installed model family and its own service manual before parts replacement; no Singapore-only model mapping is claimed. |
- Detail
- Diagnostic note
- What it says
- Record the exact E-code and whether it came from the indoor display, wired remote, or outdoor PCB, then arrange diagnosis by a qualified Mitsubishi Heavy Industries technician.
- Detail
- Diagnostic note
- What it says
- Record the exact RUN/TIMER blink pattern, optional wired-remote E-code, and whether the outdoor indicator is flashing before arranging diagnosis.
- Detail
- Diagnostic note
- What it says
- Stop repeated reset attempts. Isolate the system and have a qualified technician check supply voltage, inverter components, compressor wiring, and compressor condition.
- Detail
- Singapore / model note
- What it says
- Singapore Rocket YYS model family is from the Mitsubishi Heavy Industries Aircon Singapore residential page and RAC catalogue. Fault rows are from the official MHI RAC single-split indication table; no exact public Singapore YYS fault manual was found.
- Detail
- Singapore / model note
- What it says
- MHI Service Support Handbook pages 16-18 RAC indication table. This is a broad residential RAC cross-check, not a model-specific operation manual; non-residential handbook sections are excluded. Checklist cause: Compressor locking, open phase on compressor output, short circuit on power transistor, or closed service valve.
- Detail
- Singapore / model note
- What it says
- Official current MHI commercial error-table row E42. PAC/KX family applicability and display detail are cross-checked against MHI Service Support Handbook PDF pages 31, 32, 38. Confirm the installed model family and its own service manual before parts replacement; no Singapore-only model mapping is claimed.
What to check before repair
Use this split to separate safe evidence capture from the tests a technician should prove before quoting parts.
| You can check | Technician should confirm |
|---|---|
| Before taking any system action on E42, take a clear display photo and blinking-light video if the unit shows one. | Match E42 to low-pressure, high-pressure, leak, or refrigerant-cycle protection. |
| Capture the Mitsubishi Heavy Industries indoor and outdoor model stickers so the correct family row is used. | Measure operating pressures, coil temperatures, airflow, and outdoor fan condition. |
| The manufacturer lists no customer reset procedure for this code. Note whether one room, several rooms, or the whole system is affected. | Leak-check or pressure-test before recommending another refrigerant top-up. |
- You can check
- Before taking any system action on E42, take a clear display photo and blinking-light video if the unit shows one.
- Technician should confirm
- Match E42 to low-pressure, high-pressure, leak, or refrigerant-cycle protection.
- You can check
- Capture the Mitsubishi Heavy Industries indoor and outdoor model stickers so the correct family row is used.
- Technician should confirm
- Measure operating pressures, coil temperatures, airflow, and outdoor fan condition.
- You can check
- The manufacturer lists no customer reset procedure for this code. Note whether one room, several rooms, or the whole system is affected.
- Technician should confirm
- Leak-check or pressure-test before recommending another refrigerant top-up.
Pressure, leak, or airflow decision
Mitsubishi Heavy Industries E42 needs measured pressure, airflow, and leak evidence before gas work is approved. Replacement only becomes serious when the leak, compressor, or coil repair is uneconomical.
A top-up alone is poor value if the leak source is not found.
High-pressure faults often come from airflow, condenser, fan, or overcharge conditions.
Coil leaks or compressor-related findings can shift older systems toward replacement.
Mitsubishi Heavy Industries E42 questions
What does the Mitsubishi Heavy Industries E42 error mean?
Can I fix a Mitsubishi Heavy Industries E42 error myself?
Is it safe to keep running the aircon with an E42 error?
What causes a Mitsubishi Heavy Industries E42 error?
Will a Mitsubishi Heavy Industries E42 error need a repair or a full replacement?
What should I send a technician about a Mitsubishi Heavy Industries E42 error?
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Use these if the quote mentions the parts, checks, or repair path this code points to.