mypros+
Error code reference

Mitsubishi Air Conditioner Error Code E.OC2

Overcurrent trip during constant speed

Mitsubishi codesMitsubishi air conditioner codes

Overcurrent trip during constant speed - output current reached or exceeded approximately 235% of rated current during constant-speed operation.

First step from the service manual

Check for sudden load change, output short-circuit, and stall prevention operation level setting.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

MyPros+ Max

Get the full diagnostic procedure for E.OC2.

  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
  • Verified part numbers when replacement is required
Get the full procedure

$29/month · Cancel anytime · Or $9.95 3-day pass

What E.OC2 means on a Mitsubishi air conditioner

Error code E.OC2 on a Mitsubishi air conditioner indicates an overcurrent trip that occurred during constant-speed operation. Specifically, the output current from the inverter drive to the compressor motor reached or exceeded approximately 235% of the rated current while the system was running at a steady operating speed. This is distinct from overcurrent faults that occur during startup or acceleration. The protection circuit triggers at this extreme current threshold to prevent damage to the inverter power modules, compressor windings, and associated output wiring.

The most common causes of E.OC2 involve conditions that suddenly increase the mechanical or electrical load on the compressor during normal operation. A sudden load change, such as a rapid shift in refrigerant pressure caused by a reversing valve fault or refrigerant system abnormality, can force the compressor motor to draw excess current. An output short-circuit between the inverter board and the compressor terminals will also produce this fault immediately. In addition, the stall prevention operation level setting controls how aggressively the drive responds to rising current loads. If this parameter is set incorrectly or too loosely, the drive may allow current to climb into the fault range before intervening.

Diagnosis should begin with a physical inspection of the wiring between the inverter board and the compressor for any signs of short-circuit or insulation breakdown. Refrigerant charge and system pressures should be verified, as overcharge or blockage can create the kind of sudden load spike that triggers E.OC2. The stall prevention parameter settings should also be reviewed and compared against the specified values for the unit model.

Source: manufacturer service documentation.

Common causes of E.OC2

  1. 01

    Output short-circuit in compressor wiring

    Part replacement

    A short between the inverter output terminals and the compressor motor windings will immediately drive current to the fault threshold. Inspect the compressor wiring harness and terminal connections for damaged insulation, pinched wires, or loose terminals.

  2. 02

    Sudden refrigerant system load change

    Wiring / connection

    A rapid pressure spike caused by refrigerant overcharge, a blocked expansion valve, or a faulty reversing valve can suddenly increase the mechanical load on the compressor, forcing a corresponding current surge. Check system pressures and refrigerant charge level.

  3. 03

    Incorrect stall prevention operation level setting

    Wiring / connection

    If the stall prevention parameter is set too loosely for the unit, the inverter drive may not limit current quickly enough to prevent the fault. Review and correct this setting according to the specifications for the specific model.

  4. 04

    Failing or seized compressor

    Part replacement

    A mechanically worn or partially seized compressor requires significantly higher current to maintain rotation at constant speed. This can push current beyond the 235% fault threshold during otherwise normal operation.

  5. 05

    Faulty inverter board

    Part replacement

    A degraded inverter power module may produce erratic output currents or fail to regulate properly, causing a spurious overcurrent condition even when the compressor and refrigerant system are healthy.

See the test procedure for each cause

Frequently asked questions about E.OC2

What does E.OC2 mean on a Mitsubishi air_conditioner?
E.OC2 indicates an overcurrent trip that occurred while the compressor was running at constant speed. The output current from the inverter to the compressor reached or exceeded approximately 235% of the rated current, triggering the protection circuit. The system shuts down automatically to prevent damage to the inverter and compressor. A technician should inspect for wiring shorts, refrigerant system abnormalities, and drive parameter settings.
Can I fix E.OC2 myself, or do I need a technician?
Some contributing factors, such as verifying that nothing is obstructing airflow or that the unit has not been physically disturbed, can be checked without tools. However, diagnosing a wiring short, verifying refrigerant pressures, and adjusting inverter parameter settings all require proper tools, refrigerant handling certification, and technical knowledge. A qualified HVAC technician should handle the full diagnosis and repair.
Is it safe to keep using the air conditioner when E.OC2 is displayed?
No. The unit has shut down its compressor specifically to avoid damage from extreme overcurrent conditions. Attempting to force the system to run without resolving the underlying cause risks damaging the inverter board, compressor windings, or output wiring, which can turn a moderate repair into a much more costly one. The system should remain off until the fault is diagnosed and cleared.
Will resetting the unit clear the E.OC2 error?
A power reset may temporarily clear the fault display and allow the unit to restart, but if the underlying cause has not been corrected, the E.OC2 fault will return, often very quickly once constant-speed operation resumes. Repeated resets without addressing the root cause can accelerate wear on the inverter and compressor. A proper repair should be completed before returning the unit to service.
How much does it cost to repair an E.OC2 fault on a Mitsubishi air conditioner?
Repair costs vary widely depending on the cause. If the fault is a parameter correction or a wiring repair, costs are typically in the range of a standard service call fee. Refrigerant system repairs, such as correcting charge level or replacing a reversing valve, can range from moderate to high depending on the scope. Compressor or inverter board replacement represents the higher end of the cost spectrum, potentially ranging from several hundred to over a thousand dollars including labor and parts.

Related Mitsubishi air conditioner codes

All Mitsubishi air conditioner codes
View all 79 Mitsubishi air conditioner codes

78,000+ service manuals · 160,000+ error codes · 55+ brands

Get Started

$29/month · Cancel anytime · Or $9.95 3-day pass