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Kenny Z.
Kenny Z., Ford Senior Master Tech
Category: Ford
Satisfied Customers: 5210
Experience:  Auto Trans, Drivability and Electrical Specialist
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P340 error, cam shaft sensor. This seem to act up only on very

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P340 error, cam shaft sensor. This seem to act up only on very hot days so I assume a defective sensor. Where is it located and what do I neerd to replace it. Or could it be somthing else.
Hello and thanks for your question.

This code can be caused by several components. It depends if there are any other symptoms such as rough running, stalling or engine noise present along with the code. If there are no running concerns and the engine is quiet, then the sensor is suspect. The code is for the passenger side sensor. It is located in the passenger side of the timing cover just below where the valve cover meets the timing cover. (see picture).

You can test the resistance of the sensor it should be between 205 - 579 ohms. Or you can swap the sensor with the other side and drive it and see if the code switches to the other side. (P0345). There can also be a wiring concern or PCM concern.
The most common cause if there is no running problems or engine noise is the sensor. If there is noise or running problems let me know because there is a long list of possibilities with VCT solenoids, camshaft phasers, oil pressure concerns etc...
Customer: replied 5 years ago.


It ran rough after idling with the air conditioner on. The day was very hot, 109 degrees. After increasing the RPM and driving a short distance it seemed to smooth out and run fine. I have had intermittent rough running problems that always seem to clear up after increasing the RPM. This is the first time the check engine light came on.

It sounds like there is a VCT solenoid/valve block or camshaft phaser sticking intermittently. These are difficult to diagnose, especially if the problem is intermittent.
Usually when the problem is acting up the first thing to check is oil pressure to make sure it is not dropping to minimum. The first thing to be affected by low oil pressure is the VCT/phasers. I am attaching below what I usually respond with when there are sticking phasers with engine noise and rough running. I don't want to scare you but these engines have many issues with the VCT system. You could be at the very beginning of this issue.

These engines are notorious for phasers and VCT solenoids sticking for reasons other then the phaser itself. Cam sensor codes do not mean the sensors are bad. They can be set by any timing drive component that is making the valve timing incorrect due to over retarded or over advanced cam timing due to a sticking or inoperative phaser/VCT. The bad or sticking phaser or VCT solenoid is usually the result of the problem not the root cause. Here is a list of what I check or replace on these every time I get one in with phaser noise, VCT codes, cam sensor codes or misfires caused by VCT issues. Before any disassembly the PCM data pids for VCT error correction should be monitored to confirm it is a VCT issue. If the vehicle won’t run a compression test can also verify the VCT problem.

  • Oil Pressure. Any thing under 25 at idle will cause phaser issues. Oil pressure needs to be steady and not fluctuating. If low or fluctuating suspect crankshaft thrust bearing wear. This can be verified by a simple end play check. Also if engine is sludged in the least amount there could be oil starvation to the valve train which is also very common on these and can be verified by pulling a few cam caps on each side, it will be obvious if the there is an oil supply issue to the valve train by the condition of the caps and journals.
  • VCT valve body/solenoids. Have seen many issues with solenoid plungers sticking and restrictions in valve body due to plugged or collapsed screens.
  • Timing chain tensioner gaskets blown. This will cause oil pressure bleed to the valve train and affect phaser functionality.
  • Camshaft phasers sticking due to contamination or low oil volume/delivery pressure.
  • Crankshaft endplay, I don’t bother fixing the engine if endplay is over .010
  • Oil pump, I change anytime I replace timing drive components. There are passages in the pump that clog and can cause oil starvation problems.

In short if I don't find oil pressure concerns and my cams are in good shape I usually replace the phasers, VCT bodies, oil pump and tensioners on every one of these. Ford has updated these part numbers several times with improved engineering designs.

Customer: replied 5 years ago.


Thanks for such a detailed answer. I did a little research and this seems to be a common problem that Ford is not dealing with. I only have 50,000 on this truck and so far it's a good driver but is not holding up. I also 1996 GMC with 250,000 and it seems more reliable than my Ford. Thanks again. I will click on accept answer.

Thanks, XXXXX XXXXX this engine was not one of their better ideas.
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