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George H.
George H., ASE Certified Technician
Category: Car
Satisfied Customers: 18666
Experience:  ASE Master Tech 15+ yrs, AAS Automotive Technology, Factory trained Asian specialist
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P0340 camshaft position sensor a circuit bank one or single

Customer Question

P0340 camshaft position sensor a circuit bank one or single sensor codeCarquest doesn't list a camshaft sensor only a crankshaft sensor no one carries camshaft sensor.Please advise
97 Saturn SL2 1.9L
Submitted: 1 year ago.
Category: Car
Expert:  Ron Z. replied 1 year ago.
This vehicle does not have a Camshaft to speak. The job of the Camshaft Sensor is done by the Ignition Control Module. The ignition module contains circuitry to determine camshaft position without using a camshaft sensor, by use of compression sense ignition (CSI). The ICM is located under the ignition coils (image below). Carefully inspect the electrical connector and wire harness for any loose, broken or damaged wires. If the visual inspection checks ok, replacing the Ignition Control Module will solve this problem. For an image location view of the ICM, click here: my answer has helped you, please help me and rate using the stars at the top of the page or 'accept' my answer.Rating or accepting my answer does not cost you extra. It allows me to be credited for this Q&A. If you cannot rate or do not see where to rate, please let me know! You can ask follow-up questions after you rate or accept. Thank-you!
Customer: replied 1 year ago.
We replace the ignition control module all with a new one from Carquest and we're still having the same problems. The camshaft code I gave you comes up as soon as we start the car and the car is bucking when you drive it. The spark plugs and wires look good. Sprayed for vacuum leaks and cannot find any
Expert:  Ron Z. replied 1 year ago.
Make sure the ignition coil for cylinder #4 is firing correctly. If this ignition coil is not good, then the ICM cannot calculate camshaft position, as it uses cylinder #4 pulses to do this. An in-line spark tester should show this very quickly. If the coil for cylinder 4 is firing, there is a flow chart to follow. I've wrapped up the flow chart here:
Customer: replied 1 year ago.
Can you explain how to do that I'm not sure what that piece of test equipment is I need a little explanation on the flowchart
Expert:  George H. replied 1 year ago.
Hello I will help you with your question, Different expert here. Can you check how the spark plug wires are connected to the coils. When you stand in front of the vehicle you should have 4,1,2,3 from left to right. The cylinders are 1,2,3,4 from left to right. Let me know if the order is correct. Thank you
Customer: replied 1 year ago.
Yes they are wired correctly. The engine is running quite well at idle but gives a bucking sensation while driving under load up a hill. The only code is a camshaft position sensor and we replace the ignition control module in the problem seems to get worse so we put the original one back on. We also replaced the entire throttlebody with a used one that had new sensors on it and we still have the same problem
Expert:  George H. replied 1 year ago.
The way this senses cam position is through the waste spark from #4 when #1 fires. That is why it is so important that the wires be in the correct position. The next thing is to have a clean surface on the transmission and coat it with di-electric grease so the bottom of the module has a good contact to the transmission.
Customer: replied 1 year ago.
Ok we will try it
Expert:  George H. replied 1 year ago.
Let me know if the P0340 resets after that
Customer: replied 1 year ago.
OK it was very dirty under the ignition control module and the transmission we cleaned both services and put the dielectric grease there. As soon as we started up the camshaft decision sensor code came back as a pending code and it is still doing that Bucking send Sensation intermittently. Wondering if we need to replace the ignition control module now? We replaced it previously but never clean the surfaces and they were extremely corroded
Expert:  George H. replied 1 year ago.
That may be the problem, are you sure the plug wires are in good shape? Are the spark plugs correct or are they something like Bosch +4? They should be AC Delco for best results, the cheap one no platinum or Iridium. The bucking is usually due to the wires not being in the correct order. Is the crank sensor on the back oil soaked?
Expert:  George H. replied 1 year ago.
Can you see the misfire counter with your scanner?
Customer: replied 1 year ago.
Yes I can
Expert:  George H. replied 1 year ago.
Good, are you seeing any misfires? Did you see my questions above about the wires and plugs?
Customer: replied 1 year ago.
Wires look new . Wires are for sure in correct order 100%
Expert:  George H. replied 1 year ago.
OK, if the wires look new you should check the plugs, might have put some "special" ones in there
Customer: replied 1 year ago.
Ok Plugs look good and they are just basic copper plugs but I will replace them in the wires anyway because it's a lot cheaper than the ignition control module
Expert:  George H. replied 1 year ago.
Worth a try, I don't know what you have available but a used module from a running engine would be my choice rather than a questionable new one