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WHY does a Crank sensor fail? Need help.

Thanks everyone, for doing so much explaining of how these things work. Yeah, I'm curious if there's some kind of alternative CPS that could work better.

Whatever the route, I wish the guy who buys parts for AZ would notice that every one that gets sold gets returned 2-3 times before eventually the customer gives up and buys a real one. Seems like they'd be taking a loss from the warranty replacements at some point.

So the dealership here said Mopar hasn't made a CPS that anyone could get since 2018. I guess I'll look for it online.

Heat shield sounds like a good idea!

I think I want to run the wires straight from the PCM down to the CPS and bypass the stock wiring harness. I got a couple of plugs from the U pull it yard and they can be taken apart and rewired with new wire, but I need to get the metal pins to go into them. Anyone know a good source for
Will some sort of heat shield work for the CPS similar to what many use on their injectors?

Might be worth a try. The problem is that you will never know if that was it or if it was just a good sensor.
The life of electronics is shortened when it is exposed to high temperature. In the nuclear power industry, specifically the containment area of the nuclear reactor, electronics must last 40 years operating at some specified temperature. Instead of testing the electronics for 40 years at the specified temperature, there is a short-time procedure that can be used that exposes the electronics to a higher temperature for a shorter time. If the electronics survives this test, the electronics is considered to be able to last 40 years in the specified environment temperature. The accepted test procedure uses the Arrhenius equation. IIRC, you plug in the spec values(say 40 years life at 100F) and the higher test temperature you want to use(say 300F) and the equation gives the length of time the electronics must be exposed to 300F. If the electronics survives the shorter test, it is considered to last in the environment it operates in.

Also, though the aluminium bell housing is a large heat-sink, the "killer" here is the radiant heat impinging on the CPS from the hot exhaust headers. Poor quality encapsulating plastics gas off their plasticizers, become brittle , crack open, break coil wires,allow moisture in, etc.. Likewise, I would suspect that some poor quality "permanent magnets" are heat/shock sensitive and quickly lose their "permanent magnetic strength".

Best regards,
Yep, that's why there's three grades of parts in electronics: Commercial, Industrial, and Military (listed in ascending order of tolerance for heat/vibration/etc.).

As to the bellhousing on the trans being a heat-sink, while I don't disagree about the "impingement" from the headers, there's also the fact that the bellhousing is getting heat from both the engine AND the transmission.
With my 8 Cherokees, all of the CPS lasted to at least 150,000 miles, and usually more. Another genuine Jeep part should last that long again. The rust will kill 'em before the next CPS goes out.

Don't overthink it.