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P0340, P0341 camshaft sensor

johndaysGT

johndaysGT

New member
Has anyone had these codes come up and have successfully corrected the problem? Are the cam sensors problematic on these cars? I do have a GXP.
 


I just had mine do it again last week. First time I cleared the code and it stayed away for a few months. Then last week, it turned over for the full cycle and didn't start up initially. Second attempt it started and ran normal. So I replaced the cam sensor yesterday with a GM replacement. Code was cleared before replacement and battery disconnected while doing the change. I found it easy to do from up top, relocating the fuse box a few inches to the fender side. Do it with the engine cold though. Tried when it was still warm, with gloves and the sensor would not come out. It turned but never would give. Came right out with it being cold.

Code came back 3 starts later with same symptoms. I did check the wiring and such and it looks fine. I'll have to give it a few days and see how it goes.
 
Thank for the response. From what I've read here on the forum and from Google searching it's not always easy to correct the problem. More so than not, just replacing the sensor doesn't correct it. I wonder if my tune is in some way interfering with the readings the pcm is receiving from the sensor.
 
I'm going to try to replace the crank sensor as well as it can cause that issue. No idea if I will need to take it to a dealer for a crank pos relearn or not. The other thing that could cause it is a worn timing chain but since I am only at 89k, I figured it might be too early for that business. Never know though.

I know mine threw the code initially when I was still on the stock pcm tune. I am running with one of Lew's Diablo tunes at the moment. Not positive if the tune can do that but in my case, I don't think it affected it.
 
I'm running a Lew tune as well. I asked him about it. He said the tune wouldn't cause this code. The engine light has gone off now. Haven't seen it since about three days after posting this thread. I did find somewhere online that bad plug wires can cause the sensor to spike. I may follow that up if the light comes back on.
 
I thought this through and if the crank sensor wasn't working properly, I am positive the engine would not start at all. Took it in to have the ecm checked and voila, ecm is not talking to the cam sensor at all. I have a new one already and I'll have the dealership put it in since I don't have access to a Tech II. Wed is my appt, afterwards I'll have to put the tunes back in for the trans/engine. I'll let you know if this fixes the issue.
 


ECM was not my issue. They replaced it, same problem. So we put the old one back in, and ordered another new cam sensor. Seems the brand spanking new sensor I put in was defective. The second new cam sensor fixed the issue.

How many miles on yours, John?
 
I have a little over 72,000. I believe i'll go ahead and change the sensor. I didn't want to start throwing replacement parts at the car without getting some info on the problem first. I had an issue on my 02 Grand Prix where I had changed three sensors (all recommended by the dealer) to correct a problem. Turned out to be my reprogrammed pcm that was screwed up. I probably over analyze problems now, but it saves me money to do so.
 
Here are my findings for my particular problem. At the time I started this post I had a custom tune by Lew and an open cone intake. My car is under warranty so I decided to let the dealer take a look at it. I reinstalled the factory airbox and the stock tune. By installing the factory tune of course my codes were cleared from the pcm. I then drove the car close to 1500 miles to get the codes to set off again so the dealer could analyze the problem. The codes never returned. The hard to start problem I was experiencing never returned. I reinstalled the custom tune with the stock airbox in place. I've driven the car around 2000 miles and everything is good. No problems at all. I don't know if heat from the engine bay caused the problem with the pcm tripping the codes or what. I know the stock airbox shields it from engine bay heat. I'm going to reinstall the open cone intake and wrap the pcm in insulation and see if that helps.
 
the Cam sensor is on the passenger side away from most engine bay heat. either the tune by lew wasnt completed or their was a issue in general with timing multipliers and other PCM tables that set off the code. wrapping your PCM is a horrible idea as insulation will keep heat in and not shield it, but heat soak it more.
out of the FSM here were the issues to set it off

[h=3]Conditions for Setting the DTC[/h]Important: The ECM detects engine movement by sensing the airflow through the MAF sensor, when airflow is greater than 3 grams per second, or by sensing crankshaft position (CKP) sensor pulses.
• The ECM detects that the starter is commanded on and the engine has been cranking for more than 4 seconds without a CMP sensor pulse.
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• The ECM detects that the engine has started, but did not receive a CMP sensor pulse during the first engine revolution.
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• The ECM detects that the engine is running, but does not receive a CMP sensor pulse for 800 of 1000 engine cycles.

If the problem comes back you know what conditions set the code now.
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I reinstall my open cone intake today. Take the car out for a spin and the p0340 code comes back 4 miles from the house! I'm at a loss.
 
johndaysGT said:
I reinstall my open cone intake today. Take the car out for a spin and the p0340 code comes back 4 miles from the house! I'm at a loss.
Click to expand...
Well if youre not tuned for the extra airflow i coiuld see this happening. Maybe add some pipe to the intake to slow the airflow over the maf and see how it goes, otherwise this will keep happening. FYI your open cone will work good on the 3800 motors but not so much LS4's the IAT's skyrocket in the LS4 engine bay, and pulls a substantial amount of timing on these cars.

and again straight from the FSM:
Important: The ECM detects engine movement by sensing the airflow through the MAF sensor, when airflow is greater than 3 grams per second, or by sensing crankshaft position (CKP) sensor pulses.

 
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