Display shows F4 and the cooker will not enter or maintain pressure mode.

Safety first: Never attempt to bypass pressure safety switches. Unplug the unit before internal inspection.

• Observe behavior: If the cooker heats but never indicates pressure or immediately aborts, F4 may be related to the safety pressure switch.
• Internal check (advanced): With the bottom cover removed (unit unplugged), locate the pressure switch (often a small round device connected to the pressure chamber). Check for loose connectors or obvious damage.
• Mechanical test (advanced): Gently press the switch actuator (if accessible) to ensure it moves freely and is not stuck.
• Do not short the switch: Bypassing the switch can create a dangerous overpressure condition.
• Professional service: Replacement of the pressure switch or control board should be done by a qualified technician.