Hi,
Recently, I replaced the head gaskets on my 4.6. It wasn't fun. But, I put it back together and it ran great for a couple of weeks. I replaced several sensors along with the rebuild including the crankshaft sensor. After a couple of weeks, I got a P0315 code. I read that the PCM hasn't relearned the crank position. Great. I replaced the crank sensor because it was an easy place to start without spending a ton of money.

I cleared the code and there wasn't a code for a few days. Then, it came back. It came down to paying $70 at the dealership for them to put it on the computer or buying a new re-flashed PCM, which I did. It worked great for a few days and then the code came back. I cleared it and tried to do a re-learn by getting up to 60mph and dropping to 35mph several times as several people suggested. It didn't work and the code came back...like an irritating fungus!!

Tomorrow, I'm taking it a shop to get it on the computer.

In the meantime, I'm worried. I seriously doubt I would do this-but what if I put the pulse wheel back on backwards? Would the truck even run? or start? That's my fear!! I did unplug the sensor and the truck wouldn't start..and plugged it back in and it's fine.

Do Ford 4.6 PCMs need to go through a relearn somehow or does it need to be programmed by a scan tool?

2 crank sensors later...a new PCM...WTH?

Thanks for any info, condolences, sympathy, etc.
Charley

 

Found an oldie that might help ya...
https://www.f150online.com/forums/v8...944-p0315.html

 

Thanks...but I saw that one and it didn't really help. I did take it to a mechanic with a Snap On scan tool. The code didn't even register but the check engine light was on. According to the tool, the truck was running great-- no misfires or issues. He did read (paraphrase) what it said--which was it needed to have a certain number of warm-ups to 175 degrees for all of the sequences to happen in order. Basically, let it warm up for about 15 seconds in idle, and drive it about 40mph until it warms up. Hopefully, I heard all of that right. Eventually, the check engine light will go off on its own. He cleared the code and we'll see if it comes back on. He put it on the computer for free, which I'm grateful for--what a great guy. I'm also glad I put the pulse wheel back on the right way.

 

Ever find out what this issue was ? I know it’s been a while but I’m having this issue now with a truck I just purchased

 

Matt, please start a new thread and provide all details about your truck and the issue you are having. The original poster has not logged on since he made those 2 posts, which was 6 years ago.

 

Yes, the computer doesn't automatically clear the code when you replace a sensor. It takes 75+ miles of of driving before the computer relearns the new settings. This has happened several times. Recently, I was having issues with the idle surging. I replaced the idle control valve (a little better)and then the idle position sensor (better most of the time, but intermittent surges). My neighbor came over with a Snap On scan tool and found nothing. No codes either. I drove it about 80 miles after installing the 2 parts and it stopped all surging and works perfectly.
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im still trying to diagnose my issue now , should I start by replacing the sensor? I have it off now and debating

 

So I changed the sensor yesterday and cleared the code , drove it to work and on the way back it came back on , same code . So do I just keep driving it and maybe it will go off ? I did the relearn procedure there and back from work it’s maybe a little over 20 miles there and back

 

Matt, please follow up in your own thread instead of this one.