Diagnosis
F9E1 is a water temperature fault. The water did not reach the target temperature within a set time, usually because the heating element is failing or the wash temperature sensor is out of spec.
How to Fix It
First, ensure you are using a hot water supply. Run the hot water at the sink next to the dishwasher until it's hot before starting a cycle. If the error persists, the heating element needs testing as described in the drying problem fix. Replace it if it shows no continuity.
If That Didn't Work
The wash temperature sensor (thermistor) is likely faulty. It's a small probe near the heating element. Unplug the dishwasher. Disconnect the sensor and measure its resistance. At room temp (70°F), it should read about 50k ohms. If it's far off, replace the sensor, part number W10101070.
Heads Up
Do not ignore this error. The dishwasher uses heat to activate detergent and sanitize. Running with a failed heater will result in poorly cleaned dishes and can allow bacteria to survive.