E4 appears during preheating or pressure build-up; cooker aborts the program.

Safety: If the cooker is hot or under pressure, do not open the lid. Unplug and allow pressure to drop naturally until the float valve falls.

• Clean steam release valve: Once fully depressurized and cool, remove the steam release valve cap on the lid. Clean it under warm water, ensuring the vent hole is clear. Use a toothpick to gently clear any food residue.
• Clean anti-block shield: Remove the metal or plastic anti-block shield (splash guard) inside the lid. Wash thoroughly to remove starch or foam buildup. Dry completely before reinstalling.
• Check silicone sealing ring: Inspect the large silicone gasket for deformation, swelling, or food stuck in the groove. Clean and reseat it evenly around the lid.
• Test with water only: Fill the pot with about 1 liter of water and run a short pressure program. Observe if E4 reappears. If it does, the pressure sensor or control PCB may be misreading.
• Service recommendation: Persistent E4 with a clean lid assembly indicates a faulty pressure sensor or control board. These are safety-critical components and should be replaced by a qualified technician using ProfiCook-compatible parts.