My 2004 4.0 V6 just suddenly quit running while on the highway! Had it towed home, checked with my OBD2 reader and it set P0320. I looked up the code and it said possibly the crankshaft position sensor (CKP) is defective or the plug/wiring is bad. So where do I start?

Truck has 144,000 miles; never missed a beat until about a week ago when at about 20 mph in traffic, there was what felt like one instantaneous misfire and then back to normal. I checked for a code, nothing there. Today when it quit, it set the P0320. I had it towed home.

Any tips here would be SO appreciated, especially any that might let me fix this at home. I really can't afford the Ford Dealer nor can I trust any of our local small-town shops. So far in my 86 years, I've never had to take a car to a shop for anything like this . . .

 

Very unusually for a crank sensor to fail

P0320 is not a crank sensor code specifically
P0320 Ignition/Distributor Engine Speed Input Circuit Malfunction

These are crank sensor codes specifically
P0335 Crankshaft Position Sensor A Circuit Malfunction
P0336 Crankshaft Position Sensor A Circuit Range/Performance
P0337 Crankshaft Position Sensor A Circuit Low Input
P0338 Crankshaft Position Sensor A Circuit High Input
P0339 Crankshaft Position Sensor A Circuit Intermittent

P0320 is a timing code
Crank and/or Cam sensor were showing "out of time" with each other
On the 4.0l SOHC either is not hard to change
Can also be the computer failed or your timing chain failed

Its a good sign that computer did set a code, means its partly "sane", lol
Turn on the key
CEL(check engine light) should come on, that means computer has powered up
Try to start engine, CEL should go OFF as soon as engine starts to spin, that means computer is getting a GOOD signal from crank sensor
If CEL stays ON or flashes then change the crank sensor

Google: How to Replace Crankshaft Position Sensor 98-11 4.0L V6 Ford Ranger
Watch the 4 min video

While changing the crank sensor have a good look at its "Tone Ring", seen here: https://i.ytimg.com/vi/VqWc4Yoelro/maxresdefault.jpg
Two different kinds
The "teeth" are what the crank sensor detects passing by when crank is spinning, there is one "tooth" missing, that passes bu sensor at #1 TDC, that's the timing computer needs

 

Hey Ron D! Thank you for your detailed assist. Tomorrow I'll get under my truck to see what I can see down there. I just had all that fan-shroud stuff out to replace the A/C low-pressure line that goes down there behind the crank pulley, but hey, at least now I now how to do that part. What's your take on buying an aftermarket crankshaft position sensor for 1/3 the price of Motorcarft? I'm suspicious of the connector since there was a bit of rust and corrosion around there, and since I'll need to pull the sensor to get the connector undone anyway, I may as well replace it. I'm 86 years old and getting under vehicles is no longer easy for me, but hey, I'll do it once more. Just like i said last time!

Stay tuned!

 

Just looked at an online parts source's list of CKP sensor offerings and they didn't seem too dear at all.
They listed Denso as an OE supplier who's replacement was ~33% less expensive than the Motorcraft.
Never has a Denso product disappointed me. I used their O2 sensors on my 4.0l. as well as other vehicles over the years.