Bosch Dishwasher Error Code E1

E1 on a Bosch dishwasher means the control board detected a heating error. The dishwasher monitors water temperature using the NTC thermistor and expects the heating element to raise water to a target temperature within a set time. When that does not happen, E1 is logged and the cycle is halted. The fault can involve the heating element, NTC thermistor, hi-limit thermostat, flow switch, or the heater relay on the control board.

You should not continue running the dishwasher with an active E1 code. The machine has stopped the cycle specifically because the heating system is not working correctly. Running cycles without proper water heating will result in poor cleaning and failed sanitization. More importantly, if the flow switch or hi-limit is the cause, there is a risk the heater could run without adequate water contact, which can cause additional component damage. Address the fault before resuming normal use.

Yes, a faulty NTC thermistor is a genuine and relatively common cause of E1. The NTC reports water temperature to the control board throughout the cycle. If it has drifted out of its correct resistance range or has failed open, the board either sees an implausible temperature reading or loses the signal entirely and triggers E1. At 72°F the NTC should read approximately 55k ohms. A reading significantly above or below this, or an open circuit reading, confirms the NTC needs replacement.

Start by unplugging the dishwasher and using a multimeter to test the key components in the heater circuit. Check the heating element for approximately 11 ohms, the flow switch for approximately 0.4 ohms, the NTC thermistor for approximately 55k ohms at room temperature, and the hi-limit thermostat for approximately 0.3 ohms. Also inspect the wire harness for burned or corroded terminals. Replace whichever component reads out of specification. If all components test correctly, inspect the heater relay and solder joints on the control board, which may require board replacement or professional reflow.

Cost depends on which component has failed. A replacement heating element typically runs $40 to $90 for the part. An NTC thermistor or hi-limit thermostat is usually $15 to $40. A flow switch is in a similar range. If the control board's heater relay has failed and the board needs replacement, expect $100 to $250 for the part. Adding professional labor typically brings the total repair to $150 to $400 depending on your area and the part involved. Testing components yourself with a multimeter before ordering parts avoids unnecessary spending.