P0340 before and after replacing sensor
 

Ok so I normally don't make these but this one has me scratching my head.

I had to replace my camshaft position sensor because a CEL would come on every once in a while, and I bought an Amazon el cheapo for $15 and it seemed to have done the trick... For about 6 months.

Now I have that code coming up again, so I went with a more reputable brand (DriveWorks). And again, the issue went away... For 1 week. Now every time I start the car, I get that damn code again. I clear it, it never comes back until I start the car again.

When I pulled out the el cheapo sensor, it did have a look at what oil is (there was a single bead on it), so when I put it back in and take it out (like a dipstick) nothing really there. So it rules out gasket leak.

The car also does not start hard, like it did when I first had to replace the sensor, and the shifting overall is smoother (although that may be placebo).

I do have an appointment with a mechanic later this week, but I would like to get some feedback first - maybe I'm missing something simple.

EDIT: It would help to post what I'm driving...
'07 Pontiac G5 GT, all stock except SRI. Never any problems with that filter, although I will need to replace it in the Spring.

Maybe you have an issue with the wire or connector and when you replace the sensor you temporarily fix the connection. You could disconnect the sensor and reconnect it again and see if your issue is temporarily fixed again. If it his you might try cleaning up the connector and applying some dielectric grease.

I looked up what that grease was on YouTube I see what you mean. I'll have a look again on my lunch break and check the connectors.

I also need to buy a new bolt screw for that sensor as well, the head isn't in good shape from the previous mechanic (before I learned how to do it)

So the mechanic told me that the new sensor is faulty. But he also thinks it might be the intake camshaft actuator as well. This doesn't make much sense since that code doesn't show up...

It's not the typical code for it, but maybe the solenoid is going bad. Have you replaced those recently or ever? Or cleaned them?

The only thing I've cleaned manually was the TB. Otherwise I've ran Seafoam a couple of times.

p0340 is a code for the cam sensor electrical circuit. the electrical circuit consists of the sensor, the wiring to the pcm, and the pcm itself. this is not a performance code, meaning the sensor is losing a signal, or the cam isnt where its supposed to be (indicating the cam actuator). if it had issues with those things it wouldnt be setting a cam sensor electrical circuit code.

being you swapped the sensor twice now and the code keeps coming back, i doubt its the sensor. new parts can fail or be dead out of the box, but having 3 sensors doing the same thing is very rare. have a look at the electrical connector there could be some corrosion on the pins, or simply the pins are loose. you can take the connector apart and clean the terminals, and using a pick, you can tighten the pins up so they have a little more tension on the mating terminal in the sensor. also, trace the wiring back to the ecm, do you see any rub marks on the harness/loom, teeth marks from rodents, or any damage? check the ecm connectors, make sure they are dry and free of corrosion. if you have a multimeter you can do a resistance test of each wire in the cam sensor circuit between the ecm and the sensor. if one wire has high resistance it likely is corroded internally and causing your problem.

there is more to the code than just the sensor.

#1 quit buying cheapo parts. These cars hate aftermarket electrical sensors. ACDelco or don't even both.

Lets start there and then report back.

My suggestion is to check the resistence of the solenoid valves. I can't remember the resistance they're supposed to be, but it's around 10 Ohms. If they test good, try cleaning the valve itself and see if the problem goes away. It's pretty simple and won't cost anything to troubleshoot.

Sharkey is smarter than me though.

They did check the wiring and said that was fine as well. I've been trying to get my hands on AC Delco, but settled for this instead because it was in stock. Guess I'll need to order it online and return this one.

The connectors look ok, I can take pics when I'm done work. I'll clean them out anyways, winter has been bad for the dirt everywhere.

So I may indeed need to look at the actuator sensor as well then.