E3
Bosch Outdoor Low-Pressure Protection / Refrigerant System Undercharge

E3 appears and the outdoor unit stops; compressor may not start or stops shortly after starting.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Low refrigerant charge due to leak in Bosch flare joints or coil, Blocked expansion device or capillary, Faulty low-pressure switch (if equipped), Severely restricted indoor airflow causing low suction pressure

How to Fix / Troubleshooting

Safety first: Do not attempt to open the refrigerant circuit yourself. Refrigerant handling must be done by licensed personnel.

User-level checks:

  • Clean indoor and outdoor coils: Ensure indoor filters are clean and the outdoor condenser coil is free of debris, leaves, and dust. Use a soft brush or low-pressure water spray on the outdoor coil with power off.
  • Check for obvious leaks: Look for oil stains on flare connections at the outdoor unit and near the indoor unit connections. Oil marks often indicate refrigerant leaks.
  • Verify mode and setpoint: Make sure the unit is set to Cool mode with a temperature at least 3–5°C below room temperature.

Technician tasks (do not DIY): A Bosch service technician should connect gauges, check suction pressure, locate and repair leaks, replace the filter drier if present, evacuate, and recharge the system to the specified charge. They may also test or replace the low-pressure switch or sensor.

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Repair Difficulty

Professional Required 5/5

Required Part

Refrigerant Circuit (Leak Repair and Recharge)
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