Overheating ignition interlock is known to heat up the key on these year Accords, Civics etc.
As far as Honda is concern that has been the only reason the key has been overheating on these vehicles.
I have attached the diagrams for the ignition interlock as well as the wiring schematics for your reference.
Please let me know of any questions.
Images (Click to enlarge)
Thursday, September 16th, 2021 AT 8:02 AM