That will likely discourage *most* DIYers. If you installed a PTC *at* the coil, effectively in the coil lead, I wouldn't expect it to be as well respected.
Or, survive the sorts of abuse it might encounter.
Preventing people from tinkering is hard. Folks tend to think they know more than they do (D-K effect). And, that the "problem" is simpler than it actually is.
This is why you see home wiring that isn't up to Code -- or is downright wrong! E.g. someone had replaced a "three-way" (SPDT) switch in our garage with a regular (SPST) switch and reasoned that the "traveller" should be connected to the little green screw as there were no other screws on the switch! As a result, depending on the position of the *other* three-way, the frame of the switch would see lone voltage and gladly deliver a shock to anyone who touched it!
I encountered an old pin table that had *four* score reels crammed in place of the THREE that the machine was designed for. "Why doesn't it work?" (rolls eyes)
More than one where the blades of the EoS switch were "tied" together. Etc.
I'm sure, in each case, someone THOUGHT they were fixing an existing problem...
Does the original board treat all of the coils the same? E.g., often lamp circuits are driven differently.
I tend to dislike protection devices that don't alert to their firing. A problem can persist and never be noticed nor rectified. E.g., a blown fuse requires replacement; a circuit breaker requires reseting, an irritated watchdog requires diagnosis.
"Relying" on a protection device (because you didn't realize it was being engaged) is a risky strategy.
But, only if there are other mechanisms to ensure the board goes to a RESET state (i.e., ALL of the I/Os fail "secure"). In my case, power to the field is shut off by reset, regardless of whether or not the processor is even present in the circuit!
Remember to verify that any device that you use doesn't get upset if it is OVERused.