The HE error code denotes a heating problem. Please, look in the heater assembly: most likely, the heating element or thermistor is not working properly. Check the wiring harness as well. First, try resetting the machine. Unplug it and wait for 30 minutes. Then run a cycle. If the error comes back, you need to replace one of the two components (or both) or fix the wiring.
Other LG dishwasher error code: