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2005 f-150 4.6 , I was returning home 3 days ago on the hiway and the
engine light came on 40 miles from home , truck ran normal all the way
home , parked until today, it started and runs fine, went to the NAPA
store 25 miles on the hiway at 55 mph the NAPA guy checked with his
diagnostic and it read ; P0315 crankshaft position system variation
not learned . I had him clear the code and then drove to town at 60-65 mph
35 miles, then in town for about 5 miles city driving , then back home
at 50- 65 mph for almost fifty miles ,idled through town, the truck runs
normal and the engine light never came back on . Can anyone tell me
why this p code came up and has not returned as of yet . I'm a little
nervous about it as I have to make a 750 mile round trip in about 10 days
or so . Any input greatly appreciated , thanks , Kris
Possible causes
- Faulty Crankshaft Position (CKP)
- Crankshaft Position (CKP) sensor harness is open or shorted
- Crankshaft Position (CKP) sensor circuit poor electrical connection
- Damaged crankshaft pulse wheel teeth
Tech notes
Visual inspection of the Crankshaft Position (CKP) sensor and crankshaft pulse wheel teeth for damage. If crankshaft teethes are OK, replaced the Crankshaft Position sensor.
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Engine fails to start
- Engine runs rough
Is it possible your PCM memory got reset just before your road trip? (Replace Battery or have to jump start it?) If so, you may have no problem at all and simply drove too steady - for too long - for the PCM to 'relearn' its Misfire Tables. A quick read of these two pages from the Motorcraft THEORY OF OPERATION MANUAL should put your mind at ease. http://www.devoll.com/public/OBDII-M...RE-MONITOR.pdf The very last paragraph describes when your Code P0315 is set.
It probably has worked itself out by now, or you could consciously create the conditions for relearning the Misfire Profile. If it continues to happen - follow @steve(ill) diagnostic procedure.
Is it possible your PCM memory got reset just before your road trip? (Replace Battery or have to jump start it?) If so, you may have no problem at all and simply drove too steady - for too long - for the PCM to 'relearn' its Misfire Tables. A quick read of these two pages from the Motorcraft THEORY OF OPERATION MANUAL should put your mind at ease. http://www.devoll.com/public/OBDII-M...RE-MONITOR.pdf The very last paragraph describes when your Code P0315 is set.
It probably has worked itself out by now, or you could consciously create the conditions for relearning the Misfire Profile. If it continues to happen - follow @steve(ill) diagnostic procedure.
I never saw this on my 04, but I had this code appear on my 2015 F150 5.0 after having the computer reflashed to cure a harsh downshift problem. They fixed it with the scan tool at the dealership.
Thanks guys ,I read the theory of operation link above , I'm
not a tech guy , although I did understand some of it ....... ,
I've owned the truck for about 2 1/2 years it currently has
150,000 plus miles , never have had a dead battery and I never
have disconnected it either , the only problem I've had is in the
first six months had two ignition coils ( 6 months apart ) fail
and a third coil fail about year after that , other than that the
motor has and still does run fine with normal gas mileage ,
the motor was and is running normal before and after the
p0315 code came up and then cleared by the guy at NAPA ,
I haven't driven the truck since my last post I will report back
after the next time I drive it , I've made the same trip many
times before ( the one when the 0315 code came up ) so the
way I drive it is always the same as far as the stop and go
part of it goes .... , so the mystery still continues in my mind.
Took the truck to town today , 45 miles round trip at 40 to 60 mph
4 miles in town , motor runs normal , no codes came up ....., so it's
a mystery to me as to why the 0315 ever came up in the first place .
I never saw this on my 04, but I had this code appear on my 2015 F150 5.0 after having the computer reflashed to cure a harsh downshift problem. They fixed it with the scan tool at the dealership.
I have a 2015 5.0 and it wont change up at full-throttle... so i checked the DCT codes and got PO315... did you have a problem with changing up as well? (my downshifts are fine)