Bosch F20

Bosch error code F20 indicates: Bosch Serie 4 / Serie 6 / Serie 8 / HomeProfessional EcoSilence Drive: Unexpected heating fault F20; heater energized during cold rinse or water heats up without active command..

The primary root cause for Bosch code F20 is: On Bosch washers: Welded heater relay contacts on power PCB, ground leakage shorting heater to chassis, or corrupted NTC analog feedback signal..

To resolve error code F20: Check heater relay contacts for continuity when unpowered (must be normally open, infinite resistance). Replace power control PCB if contacts are shorted. Turn dial to 6 o'clock (down), hold Spin button, rotate to 7 o'clock, release Spin button, turn to 12 o'clock (Off).

Resetting power (unplugging for 5–10 minutes) clears temporary memory errors. However, if Bosch code F20 persists, the physical component causing On Bosch washers: Welded heater relay contacts on power PCB, ground leakage shorting heater to chassis, or corrupted NTC analog feedback signal. must be inspected or replaced.

Set a digital multimeter to ohms (Ω). Disconnect power and test NTC Temperature Sensor Probe (Thermistor) across Across sensor pins 1-2 (unplugged harness). Expected nominal reading is 4.8kΩ–12kΩ (at 20°C–25°C). Tolerance: Negative temperature coefficient: resistance drops smoothly when warmed with fingers. OL = open circuit..

Standard electrical safety protocol: 1. Disconnect 230V mains power before opening panels. 2. Verify zero voltage at test points. 3. Allow hot water or heating elements to cool below 30°C before handling.