I just started having this issue today. I have a Creality Ender3 Pro with a CR Touch recently installed. I started a print this morning that failed because it was stuck at 203 °C, when it was trying to heat up to 210 °C. I read a new articles on the E1 error message that I received, and watched some tutorials on how to fix this issue, and I started by trying to clean out the extruder nozzle. I was able to set the temperature manually to 220 °C and the hot end was able to reach and keep that temperature while I cleaned out the extruder. After making sure that there were no clogs, I started a new print job, and walked away because I had rationalized that, since the hot end was able to reach 220 °C, then I shouldn't be running into the E1 error anymore. You can probably assume what happened next, the hot end got stuck at 203 °C again and I had to cancel the print.
Has anybody else had this issue before? I was reading somewhere that E1 issues can be caused by faulty wiring with either the hot end or the thermistor, but I haven't seen anyone that has posted about having the exact same issue as mine.