Safety: Switch off power at the breaker and wait for the outdoor fan and compressor to stop completely before opening the unit.

Procedure:

Access outdoor sensors: Remove the outdoor unit service panel. Locate the discharge or pipe sensor attached to the compressor discharge line or refrigerant piping.
Check attachment: Ensure the sensor is tightly clamped to the pipe with its original clip or strap and insulated if originally wrapped. A loose sensor can cause incorrect readings and E4.
Inspect wiring: Look for chafed or cut wires where they pass through metal edges. Repair or replace damaged sections and secure with cable ties.
Connector check: Reseat the sensor connector on the outdoor PCB. Clean any dirt or oxidation.
Replace sensor if needed: If the sensor is physically damaged or tests out of specification, replace it with a Gorenje-compatible discharge/pipe sensor.
Persistent E4: If a new sensor does not clear the error, the outdoor PCB may misread the sensor and require professional diagnosis or replacement.

Unit stops during heating mode; indoor unit may blow cold air briefly then shut down with E4 displayed.

Possible Causes