Washer does not heat water; cycle may run long and E05 appears

Safety first: Unplug the washer and ensure the drum is cool before working near the heater.

• Run a hot cycle test: Select a 60°C or 90°C program and feel the door glass after 20–30 minutes. If it remains cold and E05 appears, the heater circuit is suspect.
• Access heater terminals: Remove the rear panel (or front lower panel on some Bosch models) to access the heater at the bottom of the tub.
• Inspect wiring: Check for burnt connectors or loose spade terminals on the heater and NTC sensor.
• Test heater: Disconnect the heater wires and measure resistance across the heater terminals with a multimeter. A typical Bosch heater is around 20–30 Ω. Infinite resistance indicates an open heater that must be replaced.
• Test NTC sensor: Measure resistance of the NTC (usually mounted in the heater bracket). It should change smoothly with temperature (e.g., ~5–15 kΩ at room temperature). Replace if open, shorted, or erratic.
• Replace heater assembly: If the heater is faulty, remove the central nut, push the bolt in slightly, and carefully pry the heater out of the tub. Install a new Bosch-compatible heating element with gasket, tighten the nut evenly, reconnect wiring, and test.