Help with camshaft position sensor issue...

weaver81 · Nov 8, 2004

Thought I would through this one out there and see if anyone has any opinion or experience with this.
About three weeks ago my 02 GT started logging a P0340 DTC (Camshaft position sensor fault). The only problem symptom is that sometimes the engine will start and then immediately die when first cranked. When this occurs it never fails to start and idle normally on the second crank attempt.
Well, since the CPS is relatively cheap and easily replaced, that was my first thing to do. The DTC was cleared and all looked normal until the second warm-up cycle of the engine, when the DTC was logged again. I disconnected the battery for 1/2 hour and let the ECM re-initialize itself. It then went about eight warm-up cycles before logging the code.
On the surface, it appears I have an intermittent fault in the CPS circuit somewhere. I'm also wondering if there is some other condition that may be inducing a false P0340 code.
I would appreciate any opinions.

02GTRX · Aug 31, 2005

any one??? I am having that exact same problem.

jstreet0204 · Aug 31, 2005

Here are the test steps from alldata. Start with DR5

seabas2020 · Jul 28, 2006

Same problem

What did you guys figure out? I'm having the exact same problem!!!

Mike97gt · Jul 28, 2006

jstreet got the pinpoint test up there for you.. now what you need to do is follow those steps when the problem is acting up and you should find out what the problem is.. My bets would be on the PCM itself

Skidawg · Sep 7, 2006

I just got the same thing repaired. They replaced the sensor and it seemed to work.

They ended up also replacing the alternator because they said it was interfering with some of the electronics. (I'm not sure why this happened now, but whatever)

So far, everything is again working correctly.

bsa_victor250 · Sep 7, 2006

Im having the same problem with my 2000GT and have replaced the cam and crank sensors does anyone know what pin # at the pcm and the color I should be checking on that end of the harnes?

bsa_victor250 · Sep 7, 2006

Cam pos sensor trouble

Hey svttech76 is that a common problem? The PCM going bad? Or in you experience do you find it just a bad connection at the PCM that can be corrected ? I'm asking because you sounded sure that was the problem.

davidbezotte · Apr 20, 2007

I had the samme problem with my 2002 gt. First the check engine light came on, they replaced the camshaft position sensor and the same code of P0340 kept coming back on. Finally my alternator went all the way out and left me stranded. They replaced it and I haven't had a starting problem, or the check engine light come back on! They said the diode or regulator in the alternator was sending erratic impulses to the PCM. I'm glad that it's finally fixed. It been driving me nuts for 3 months!

Mike97gt · Apr 20, 2007

davidbezotte said:
I had the samme problem with my 2002 gt. First the check engine light came on, they replaced the camshaft position sensor and the same code of P0340 kept coming back on. Finally my alternator went all the way out and left me stranded. They replaced it and I haven't had a starting problem, or the check engine light come back on! They said the diode or regulator in the alternator was sending erratic impulses to the PCM. I'm glad that it's finally fixed. It been driving me nuts for 3 months!

Interesting.. glad it's fixed for you. Did you notice any other issues other than this code.

Maybe the alternator was some how messing with the magnetic field that the cam pos sensor works on.

Brute03 · Apr 20, 2007

i had the same thing happen to me too, i actually lost sleep because i was up searching the net for any possible answers. the shop that i go to couldn't figure it out either. the info i gathered led me to believe there was some kind of electrical interference throwing the cps off.

so i went under the hood and noticed that the alternator and the cps are on the same harness, so the next day i took it to my mech and told him to check the alt. sure enough that was the culprit, i think he said either a diode or the regulator went bad, i'm not sure

KarmaKid · Apr 22, 2007

Interesting.....

I was having this same starting issue about 6 months ago. It was very intermittant. I purchased my SCT Excalibrator, downloaded my 91+ tune and it became more far and few between. Since gas has been on the rise, I filled up with 87 octane and downloaded my 87+ tune yesterday. Then the car backfired and didnt start on first turn everytime yesterday. My engine light finally came on last night. I pulled the cam sensor code. Drove it afterwards and can hear the difference in the exhaust tone. I'm assuming the cam sensor finally crapped out. Im headed out now to buy and install a new one. I will let ya know the results in a few days. It's an 02 GT by the way.

KarmaKid · Apr 27, 2007

Grrrrrrr....

Ok, so it was Sunday and the Ford dealership was closed, therefore I ended up at Autozone for the cam sensor. Wells manufactured I believe. Easy swap, just slightly remove the power steering pump, unscrew, remove then replace. Check engine light was gone upon first start then reared its ugly face about 2 days later. Still getting the backfire/pop upon initial turn of the key, but only intermittently. I have read in a couple other threads that peeps have replaced the alternator because their mechanics said the bad alternator was electricaly disturbing the cam sensor. Welllllll, yesterday I left my running lights/fog lights on which killed the battery. I tried popping the clutch and starting a few times with no luck. Today I tried jumoing the stang 4 times. Each time it would run for a minute or two then die. So I'm assuming it ran on the teeny tiny charge from the jump, then died because the alternators *****. So I'm going to pull both the alternator and the battery and have each one tested today. Fun Fun Fun.

MrGame · Apr 27, 2007

I had the same problem and I had to replace the sensor and my alternator...ran much better afterwards

Pearl02 · Apr 28, 2007

So it seems that the alternator is the problem and not the cps? Or, when the alternator goes bad it also takes out the cps with it. I'm not having a probelm but this seems interesting. Pearl02.

Brute03 · Apr 28, 2007

no, the CPS is perfectly fine but there's something in the alt. that goes crazy causing it to interfere with the signal from the CPS, which in turn makes the computer think the CPS took a dump

KarmaKid · Apr 29, 2007

Brute03 said:
no, the CPS is perfectly fine but there's something in the alt. that goes crazy causing it to interfere with the signal from the CPS, which in turn makes the computer think the CPS took a dump

Exactly! I replaced the alternator yesterday, carged up the battery and it started right up. No more engine light and the cam sensor code is gonzo. Replacing the alternator seems to have fixed it all, runs great!

mustang462002 · May 10, 2007

I replaced the camshaft sensor. My alternator is reading 14.4 volts at the battery terminal. Is this a good way to check it. Or could the regulator still be messed up. Could it be the pcm.

gaerisch · Oct 18, 2007

gaerisch

I am having the same problem on my 03 GT. I replaced the sensor but the code came back after a few startups. I noticed now for about a year that my alternator has been making whinning noises, especially when drawing alot of amperage (e.g.-headlights on, A/C on, and the defroster). The whinning is louder now (like a Kenne Bell S/C-I wish) even without any accessories on. If I have to replace my alternator I will get a P&A alternator( because their new not rebuilt). But I would like to get a slightly higher amperage then stock. Any sugesstions?

03 GT w/C&L CAI,Accufab 75mmTB,Trickflow intake plenum tube w/Steeda spacer,Steeda X Pipe w/Cats,Magnaflow SS Cat Back Exhaust,Diablosport Tune,BBK Subframe welded.

chuck943 · Oct 18, 2007

This is usually caused by interference from the alternator caused by a malfunctioning diode or open phase connection . On most that I have seen you can usually duplicate it by starting then turning off vehicle several times in a row. When problem occurs it will want to try to/or stall then followed by the P0340 code resetting. If you can duplicate it this way then just unhook the alternator and try this proceedure again to see if code resets. Another way would be to look at alternator pattern on a scope. Ford has a tsb out on this 06-19-12 that shows good and bad patterns.

Help with camshaft position sensor issue...

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