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Discussion Starter · #1 ·
Recently purchased a 2011 Jeep Patriot 4x4 2.4 L.

I had the vehicle for a couple weeks and overall the engine and transmission and everything else worked fine.

About a week ago I also had all 4 of the rotors, pads, and calipers changed as well as 2 new tires, new outer and inner tie rod, and a 4 wheel alignment.

A couple days after those repairsI removed the battery terminals and let sit overnight as well to reset ecu and changed spark plugs and new air filter for a quick tune up of sorts.

Immediately I noticed poor acceleration but not horrible. After about 3-4 quick trips into town maybe 30-60m total drive time the traction control/esc light came on continuously and the vehicle went into limp mode where I could not accelerate much at all and it barely gets up to 40 mph.

The trusted mechanic shop I took it to checked the wheel sensors and the wheel bearings and anything else that is obvious and could not find anything. They hooked it up to the scan tool and they found the following codes. maybe/hopefully they are both related.

“P0340 camshaft position circuit”
Camshaft position sensor wiring issue?
Camshaft position failure?
PCM failure? Less likely
Crank sensor failure? Less likely

“C121C torque request signal denied”
Antilock brake system module?
Power train control module?

We also learned that my patriots check engine light bulb is burnt out or removed? The check engine light won’t even turn on like normal at start up. So the check engine light “should have been on” but we never noticed because it was not working.

My mechanic was confused by these codes because it did not direct him to anything obvious that he was familiar with and suggested I take it to the dealership for further inspection and diagnosis. I had my mechanic clear all of the codes and I drove the vehicle home. No traction control/ESC light came on on the way home. About 15 minute drive. The vehicle did still seem sluggish.

I let it sit overnight and I took it for a pretty good test drive this morning. Vehicle is running perfectly fine now with zero symptoms?? The acceleration and everything feels great. We really didn’t do anything besides clear the codes.

Cautiously excited. How long will it take for these codes to reappear if these problems are legitimate? Maybe clearing the codes just refresh the computers memory and all is well?

this vehicle is for my 16-year-old son. Hoping to get some suggestions or answers or clarity.

Thank you.
 

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Discussion Starter · #2 ·
Update. Back to where I started. Drove the Jeep around for a while. At first everything felt really great no codes or lights and then the sluggish acceleration started up again for a couple miles and then the same P0340 code and same traction control/ESC light came on in limp mode. The cheapest and most common attempt will be for me to replace the camshaft position sensor. $25. About an hour worth of work. After that that is pretty much all I can do. Hopefully this does the trick.
 

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FWIW, here's a thread with the service manual info on P0340:

The only other suggestion I have would be to get a scanner that can read and store live sensor data, so when you have a failure you can review the sensor data to see what exactly failed and when.

In any case, let us know how things turn out.
 

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Discussion Starter · #4 ·
Thank you for taking the time to review my situation and suggest a couple things. I plan to replace the camshaft position sensor this afternoon and I’ll go from there.

I read all of the posts related to the link you just shared. My patriot starts up very well and it actually drives and accelerates pretty well after all the codes have been cleared. It’s just after about 15 or 20 minutes of driving the bad acceleration starts then the traction control/ESC light comes on and I get the P0340 code. It does start up very well so hopefully my situation is not as bad as the one in this post you caught it. Hopefully mine is something electrical. Maybe just a sensor. Maybe the wiring. Maybe the PCM computer? We will see.
 

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Discussion Starter · #5 ·
Update for anyone who has read this.

I changed the camshaft position sensor and no improvement. It still starts up and idles perfectly fine but after I drive it for about three or four minutes the P0340 code pops back up and my traction control/ESC light comes on and it goes into limp mode.

I have an appointment with a specialty mechanic shop in town this week and hopefully they can hook it up to a good scanner and see what the issue is.

I have been reading about reluctor wheel/rings. That is an internal engine component that sounds pretty expensive. Maybe it is a simple electrical wiring issue. I guess we will see. Very disappointed and to the point of depressed.

interesting, it does start perfectly fine and it sits and idols perfectly fine for over five or 10 minutes with no light or issues. It is only when I put it into gear and drive it for a little while?
 

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Again, if you haven't done so, you should try to get a live data scanner to take data while you drive so you can see what is happening, click on the video below to see an example of troubleshooting a bad wheel hub with live data.






If this problem is repeatable, a competent shop with a live data scanner should be able to track it down.

Without the live data scanner it will likely continue to be trial and error of changing parts without success.
 

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Discussion Starter · #8 ·
I REALLY appreciate your reply and comments. I have an appt set up with the local Jeep dealer next week. I assume they will have a live data scanner? The dealer is more expensive for this appt compared with another local shop. I am thinking it is best to bring my Patriot to the dealer because they will have more experience with similar situations in the past? Even though more expensive?
In the mean time here are some things I found as possibilities after searching online for the past week. Some of these things listed first are cheaper and easier I am going to look into on my own.

***check wiring to and from camshaft sensor and computer
**check crankshaft position sensor and wiring
***check the spark plug coil packs and wiring.
***check air intake sensor
***check transmission fluid
***egr/exhaust gas recirculating valve. Only cad desirous versions??
***Bad MAP/manifold absolute pressure sensor?
***loose oil galley bolts in the motor (there was a service bulletin put out about it by Chrysler). From what we were told when those are loose (or fallen out like one of mine did) it changes the oil flow which can throw codes for the cam position sensors.
***Camshaft reluctor ring?
***PCM? PCM update?
***Timing belt and valve timing?
 

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Dealer service departments are not necessarily equal in their knowledge, experience, equipment, competencies or success.

If you want to know what equipment and techniques they might use to attempt to resolve the issue it is best to ask them directly rather than assume. :)

You can check for outstanding TSB's on your vehicle by entering your VIN here:
 

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Discussion Starter · #10 ·
Thanks again for the reply.

Whichever service shop I take it to I will let them know I did extensive research and I am knowledgeable about these issues.

After they do their initial diagnosis and scan I will request they check the cheapest and easiest possibilities first instead of jumping to the most expensive.

I also have a 3mth/3000mile power train warranty until October 15th. So maybe/hopefully if it is an internal mechanical covered issue the warranty will cover it.

Maybe because I have the warranty coverage I should suggest they look at any covered related possibilities first?
 

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Discussion Starter · #12 ·
Just dropped off my Patriot to have it looked at. On the way in addition to the P0340 camshaft position sensor circuit code a new P0344 crankshaft position sensor started up. Those 2 codes are now both active. Check engine light, traction control/esc light on, limp mode. I have read and watched videos. These codes are frequently related. Hopefully a wiring issue. That would be hard to locate?? Certainly could be something else. Ugh. I guess I will see what the mechanic says.
 

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Discussion Starter · #13 ·
Update.
my newest code P0344 is actually still a camshaft not crankshaft position sensor code. P0344 it’s something about signal intermittent. But still a camshaft position sensor issue. I thought that one refer to the crankshaft. I was wrong.
The mechanic hooked my patriot up to some more advanced diagnostic and electrical scanners. They tested the camshaft position sensor and the sensor was good but there was no signal and no current being sent to the PCM. They dug around and found a wire that was bad leading from the sensor to the PCM. Once they replace this wire things improved but there was still another related code so they end up changing to camshaft position sensors. They explain both of the camshaft position sensor‘s are in the same circuit so maybe while changing the wire and when I changed one of the sensors both of them needed to be changed at the same time. They say everything is all set now. This also cleared the C121C code that I was getting. . I am pretty sure the camshaft position sensor codes P0340 and P0344 caused the C121C “torque request signal denied” code. The C121C code is what triggered my traction control/stability control esc light and put me in limp mode.
I am cautiously relieved and excited that, at this time, it does not look to be a more serious issue. I am sure other things can still happen and only time will tell. Short term, this is a huge relief after the week or two of misery I have been going through.
I also learned there are two camshaft position sensor‘s? I changed one of them myself. I am yet to know when they change the “other one“ which one did they change. The one I already changed or the other one? I had no idea they were 2. Maybe I replaced the wrong one. The camshaft position sensor I replaced was in front of the engine nearest to the front bumper. I guess there is another one on the back of the engine? When I pick up the vehicle tomorrow I will ask him which one they changed.
Hopefully this is the last that you hear for me and hopefully this helps someone else moving forward.
 

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Did you ever figure out the root cause of your issue? I'm chasing the same problem and would love an update.

Mine started with a "no bus" error and the car sometimes refusing to start, sometimes starting then shutting off after a few seconds. I was only getting 11.5 volts off the battery though, so first I swapped that. It seemed to improve the consistency? But the problem still occurred. Someone had mentioned that the "no bus" issue can be caused by a bad radio interface module that hooks into your CAN-bus, and I have an aftermarket radio, so I replaced that. The "no bus" error went away (and the no-start issue), but was replaced by a check engine light, a traction control light, and a P0344 error code.

I have a pair of Camshaft Position sensors in the mail, but when I go to replace them, I'd like to check the oil galley bolts as well, since I know that can be an issue on some Jeeps. However, if you confirmed a fix for your issue, I'd like to make sure I'm covered there as well.
 
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