Dishwasher does not heat water properly, cycle runs long and dishes are not hot at end; display shows E03.

Safety first: Disconnect power at the breaker and close the water supply. Heating components operate at mains voltage.

Steps:

• Run a diagnostic: If your Gaggenau model supports it, enter service mode (refer to service documentation) to confirm E03 and check heater test.
• Check for obvious leaks: Inspect under the dishwasher for water leaks around the circulation pump and heater assembly. Leaks can damage heater wiring.
• Access heater assembly: Remove the toe-kick, slide the dishwasher out slightly, and tilt it back (with protection for the floor). The flow-through heater is usually integrated with the circulation pump on the base.
• Test heater resistance: Disconnect the heater terminals and measure resistance with a multimeter. Typical values are around 15–30 Ω (check service specs). Infinite resistance indicates an open heater that must be replaced.
• Check NTC sensor: Many Gaggenau dishwashers use an NTC sensor in the heater housing. Measure its resistance at room temperature and compare to spec. A shorted or open NTC will trigger E03.
• Inspect wiring: Check the harness from the heater to the control module for burns, breaks, or loose connectors. Repair or replace as needed.
• Replace heater assembly: If the heater or NTC is defective, replace the complete heater/circulation pump assembly with the correct Gaggenau part. Ensure all hose clamps and seals are properly seated to prevent leaks.

Warning: Incorrect reassembly can cause water leaks and electrical hazards. If unsure, use an authorized technician.