Mitsubishi Heavy Industries aircon E42
Use this Mitsubishi Heavy Industries E42 guide to capture the fault correctly and 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. The loaded row is source-backed by official 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 matching source row
The same visible code has more than one source-backed meaning. Match the model family, system type, or reporting unit 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 row to the installed model or reporting unit, then use the source-specific 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. |
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 selected source row 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
Source-specific guidance
These diagnostic-reference notes help match the code to the exact model. Electrical, refrigerant, wiring, resistance, and component checks are technician work, not DIY steps.
| Source 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. |
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 selected source row lists no customer reset procedure. Note whether one room, several rooms, or the whole system is affected. | 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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