According to LG documentation, the dH error indicates a trouble with defrosting. I didn't check for your specific model but my answer is based on my overall experience with LG refrigeartors having defrost problems.
It basically means that it took too long for the fridge's defrost sensor to rise above a set temperature, or the PCB thinks so.
This could mean a faulty sensor, broken heating element or thermal fuse. Or damaged wiring, bad PCB, etc.
Defrost problems on LG refrigerators are often caused by the failure of part 6615JB2005C, found in the freezer compartment.
This part includes a temperature sensor and a fuse, you should get a few kOhm reading between the orange wires, and continuity between red and brown wires if it's good.
Heater can be checked for continuity, likely 80 Ohm or less.
If you have the wiring diagram of the unit, you can usually check the values from the back of the unit at the PCB to identify the failed component before ordering a specific part if you want to make the repair in 2 steps.
Otherwise, just remove the plastic panel at the back of the freezer and check the components from there as you'll likely have to open it to make the repair anyway.
Personally, I usually bring part 6615JB2005C with me, as it's not expensive to get and has a high likelyhood to have failed, confirm that the fuse is open or the sensor is way out of specifications before installing the new part, then check resistance of heating element to make sure it's not open.
Sometimes a temperature sensor can give a valid reading but be out of spec enough to cause long term issues (Pointing at you, GE pipe sensor!). If possible, let your old sensor get back to room temperature and compare it with the new part. Of course, if the new part has been unpacked, tampered with or installed, you might not be able to return it so trial and error can get quite expensive.
If the model allows for easy Forced Defrost in Service mode, I like to start a defrost cycle and check for Amperage through the heater and make sure it heats. Otherwise, you might want to either carefully check all wiring, of just let all the frost melt and open the back of the freezer again in 2-3 weeks or run time to make sure there isn't a big amount of frost back.
PCBs are the hardest thing to diagnose as they have many integrated circuits, validate that every other component is good first, let the unit unplugged for some time to let capacitors discharge, and if the trouble gets back soon, you might consider a PCB replacement.
___________Réparateur Réfrigérateur Bécancour