Ok, so I got a PO340 camshaft position sensor A circuit (bank 1 or single sensor) code that came up yesterday. Has anyone seen this before? What's the most likely cause and best way to fix it? Other than just changing the sensor. Is it a symptom of a bigger problem?

 

A lot of the time it has to do with a bad diode in the alternator. It's happened to a lot of people on here. Replacing the alternator usually fixes it. Unless of course it is the sensor.

 

Well, I went ahead and bought a new sensor. I figured what the hell it's only like $20. If that doesn't really help, no big loss and its got a new sensor. Possibly the alterntor huh? I just replaced my old battery about a month ago, hmmm. Maybe I should get my alternator checked out?

 

Bad alt. Happened to me too. If you let it go long enough, you'll get to a point where the car backfires on you sometimes, scares the **** out of people, but it's a headache.

 

Same code happened to me. Cam sensor code. I also had backfire. However, my crank sensor pigtail was broke. I replaced my crank sensor pigtail. Problem fixed. Yes, fixed my crank pigtail and fixed my cam sensor issue. Car runs flawless!!!!

 

Well I replaced the cam sensor and checked the crank sensor and its connection, but it's still pulling the same code.

 

Maybe it's time for a new alternator and crank sensor. Then I'll see what happens. Might as well upgrade the alt.

 

I put the new alternator on today and the problem seems to have disappeared. I hope this has solved that issue so I can move on to upgrading other areas. Thanks for the help.

 

Couldn't you verify if the alternator was causing it by disconnecting the alternator?

 

It's an intermittent problem. Mine would really only happen if the car was recently on. Once it was off for a bit, no issues.

 

To answer my own question(sorta). Just disconnecting the alternator did not get rid of the code. Came right back after 200ft of driving.

The alternator is still spinning though. Belt still connected. Maybe if it has a bad part(diode) it's still transmitting interference.

Next question, Can the auto parts store check the diode with their battery checker?

 

Had the alternator checked. Not that. Code still persists.

 

You'll have to have some faith and replace it. I had mine checked twice, found nothing wrong, and after replacing every electrical component there is, that was the last thing and the only thing that worked. It's a bit of an expensive guess, but it works.

 

From my experience and research into my own alternator probs (bad diode that threw the same code on my 06), Parts stores tests probably won't find bad diodes. I'd still suspect the alternator. Do you have any battery drain? A failing diode can allow the battery to discharge back through the alternator.

Or, if you've got an oscilloscope you should be able to diagnose it

 

Test from autoparts store showed .04amp drain. test passed. How will the oscope show bad?

 

You'd see an irregular waveform kinda like this:



This is what it'd normally look like (@fast idle)



Pics courtesy this site, which has a really good write-up
http://www.brighthubengineering.com/consumer-appliances-electronics/83694-how-to-test-an-alternator-with-an-oscilloscope/

 

Awesome. Gonna check that out.

 

I had my car break down over 5 months ago originally thought it was the head gasket and to white I coming out my exhaust and my whole front end smoking at a stop. Fix headgaskets and temp housing thermostat and ect twice and a radiator harmonic balancer and crankshaft brand new spark plugs and wires water pump alternator and egr valve and a brand new computer two brand new camshaft sensor and still have that code car over heats and doesnt run well its an automatic ford mustang 2005 v6 140,600 it shifts at a later rpm because of the camshaft not getting power to it wires arent bad so whats the issue?$ 1,000 later and nothing fixed any of the issues i still have

 

I replaced my alt, pigtail and sensors and still have code. Any luck with yours?

 

Hey Guys -

New to this forum and I have a question -

I have a 2012 Mustang GT with almost 112k miles - mild bolt-ons. Recently, I have been experiencing hesitant acceleration in my car, sluggish around 3k RPM when WOT. Tonight, I was driving uphill and decided to step on the gas a little and see what happens: My check engine light came on almost immediately. I have an Nguage tuner so I quickly read the codes and a P0034 Camshaft Positioning Sensor code came up. I cleared the code and drove the rest of the way home and no light illuminated. What is the problem here? I have noticed my clutch going out as well so I am getting that done this Sunday anyway but I don't think any of this has to do with the code or the lack of accerlation/power.

Any help is very much appreciated!

Jack