2007-2009 Mustang GT/CS California Special

First timer here

Old 2/19/18, 07:45 PM
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First timer here

I have a silver 09 gt and 140k miles. I got the P0340 code. I replaced factory alternator with a remanf alt from oreilys. Code still on and stang runs bad. Questions the oreilys alt the problem lol and could a 08 alt fit in my stang. ( american muscle doesnt sell 09 alts..only 05- 08) if a 08 fits id buy one...need other stangers advice..please help
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Old 2/22/18, 03:56 PM
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My advice is this, get the Denso stock OEM alternator which replaced the originals beginning in 2010 due to crapping out. Look into places like Rock Auto for the best prices. But whatever you do, don't ever buy an aftermarket replacement alternator, as they either don't fit/line up properly or just their just plain junk and btw: the "OEM" 2010 Denso alt are compatible and will, therefore, fit all 2005-10 cars!

Last edited by m05fastbackGT; 2/22/18 at 04:00 PM.
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Old 2/23/18, 07:41 AM
I tweaked the button...
...and got lucky!
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Assuming you know the code is the cam sensor. And that you've replaced the sensor(s) in question, and still getting this...

So with that, the O'Reilly's is fine. I'm running that one on my car now. It aligned just fine and works like a champ. (Aaand now I've jinxed it, but oh well. I can dremel it back into alignment I bet! ) That said, it could be the *particular* alternator is a problem, truth. Parts go out, even when new, that's life. It also could be the battery is an issue, and due to the old alternator, causing the new alternator to work hard... vicious cycle. It helps if you do both the battery and the alternator and *clean all the things, and then put grease on them.*

Read this:

That seemed to solve all the electrical wonkiness on my '06 GT. And also solved the nasty terminal issue. My terminals are still good lookin' and clean (except the dielectric grease on 'em.. and the dirt that gets attached, but oh well, terminals are nice underneath!) for a number of years now. Not to mention the electrics actually work. (Also, when I did replace the battery, I decided to get the higher CCA instead of the longer warranty, but 'standard' CCA that was available too, so maybe that has something to do with it. Car starts awesome, that's for sure. )

And yes, all '05-10 alternators are physically compatible, so you can do the 2010 Denso if you want.

However, it's been reported in them thar intar-webs that once an alternator goes rogue and starts overvolting (or whatever it does), that it'll fry the camshaft position sensor along with it (and the battery too, by the way) and so you'd have to replace the CPS anyway because the previous alternator has killed it dead.

Long shot? It might be a cam chain tensioner, but that's me graspin' at straws, and it's probably not it at all. It's not the cam chains, if it was it'd be... well, a new engine, really, if it broke like that.

Of course, inspect all wiring regarding the CPS.

Bad computer is possible... I'd sincerely hope not. Maybe it's the wiring to it...

You might want to just bite the bullet and take it to a dealer and have them diagnose it. These computer cars these days... They can 'see' things we ordinary people can't with their fancy tools...

If any of that long windedness helps...

Good luck to ya!

Last edited by houtex; 2/23/18 at 07:42 AM.
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