I know a lot of people carry spare CMP sensors in case the old one suddenly conks out. The problem I see with that is it would really be no fun if it happens to conk out on a two-lane mountain highway with blind curves and no shoulder, and you're trying to fix it while blocking half the road with crazy drivers racing around the curves. Would it be a good idea to replace the CMP preventatively after X number of miles? Can they be counted on to last a certain minimum number of miles?

 

I believe you mean the crank position sensor (CPS)? Most of them fail with some warning. My truck stalled once or twice for no reason, but I was able to immediately restart it. That was my clue.

I would drive with your installed one until the day the truck randomly stalls. Carry a Motorcraft spare and wrench in your glove box in case you cannot restart it. I would not replace it if it's not broken. Don't use a parts-store house-brand sensor (according to this forum, and I agree).

 

There is no rhyme or reason to when they fail. That said, I have owned 10 (and still own 7) in the last 16 years and work on 9 more at my job for the last 9.5 years that have NEVER needed a replacement. I had to put one in a pickup my brother owned a decade ago.....but that's it.

I don't think it's as widespread of a problem as forums make you believe. However, I do have a spare in every vehicle just in case. I don't think that I'd replace it just for grins but I would at least break the bolt loose in your driveway and put some anti-seize on it and reinstall....those bolts have a habit of self-tightening and then breaking off which would be more of a pain in the *** than just having to change the sensor on the side of the road.

 

Technically One Sock is correct in referring to the CMP, not as a CPS.



A lot of times we as consumers and customers refer to something using a different terminology than what they were called from the factory or their designation in the service manuals. Cruise control is another one, it is actually "speed control" in the manual. This can be confusing at times and will often lead a procedure or pinpoint test searcher astray if they are not familiar with the right terminology.

We get it though, CPS vs CMP... Same difference 99.9% of the time, which is good enough in a court of law when reading a DNA test.

The CPS is a scapegoat a lot of the time, but can be faulty some times. Usually it will start causing intermittent failures. The earlier trucks move the RPM needle when cranking where the later ones do not until the engine has started.

I carry a spare in my travel tool kit because I tow heavy cross country. Although, I did not carry one until a friend of mine had his truck totaled by a sideswipe accident that was not his fault. He sold me a few of his genuine OEM parts for a great price and a CPS/CMP was one of them. He is still around here from time to time even though he moved to a RAM 1500. It is a fancy truck though, so I don't blame him.

Things and parts will break on these trucks, what sets these trucks apart from the newer trucks is that most of the roadside repairs can be done on the roadside, not at a dealership costing you $100 an hour for labor.

Have fun with it, drive it and if you need advice or even an in person hand, this is a great place to be. I have driven to help FTE'rs out just as FTE'rs have driven to help me out.

 

Mine went bad and it did NOT leave me stranded - it simply made for a rough drive home. CMP sensors in these trucks are 12v Hall effect sensors. When the material inside starts to degrade, it will cause intermittent issues. P0344 will indicate an intermittent failure. This was the first cam or crank sensor that I have had fail - my friends have had some fail, but they may have been cheap aftermarket garbage. The one I pulled off was the newer "gray" part, so it has been replaced before. A 10mm ratcheting wrench and a flathead screwdriver got it out no problem. I purchased two at my local Ford parts sales (Green Sales, not a dealership) for $18 each. I ended swapping them out the next day when my truck wouldn't start, due to my dumb a$$ putting my truck in the "N.S." tune and forgetting about it. So now I have a verified working backup in my glove box.

My thread is here, but I would suggest keeping a spare in your glove box. There is no saying when the sensors will fail. The new one you put in may fail sooner than the existing sensor.