Camshaft Positioning Sensor

[Chris Pierce]

HI, I'm new to the forum so I'll lay out a few details. I have a 2005 LJ with 42k miles. This is an original Southern California jeep, I purchased roughly 1.5 yrs. ago. About 9 months ago I had the distributor replaced. In July 2016 I moved to Kodiak Alaska. 2 months ago my camshaft positioning sensor (CPS) was malfunctioning so I replaced it with a part from NAPA and cleared the engine code of 340. 2 days later it came back on. I proceeded to order another CPS from the Jeep dealer in Anchorage, AK. Set engine to TDC and installed new sensor and cleared code. The code stayed off for roughly 3 weeks. On a cold morning ( approx. 26 degrees) the jeep was hesitating to start and then fired up but threw the 340 code again, this time it threw a code of 306 as well. I replaced all the spark plugs and took the jeep in for a ECU reflash, as I read that this might be necessary after changing the CPS to resync the sensors and ECU. Two days later same thing! This only occurs on cold mornings, If its not cold the jeep starts fine and throws no codes. Does anyone have any clue what this could be or where I go from here? Any help will be greatly appreciated.

 

[Chris]

@Ted, another Alaskan!

A code P0340 obviously is a bad camshaft position sensor (CPS).

However, the code P0306 could mean any of the following:

• Faulty spark plug or wire
• Faulty coil (pack)
• Faulty oxygen sensor(s)
• Faulty fuel injector
• Burned exhaust valve
• Faulty catalytic converter(s)
• Running out of fuel
• Poor compression
• Defective computer

While I hate to guess, one thing I would check is the coil pack.

An easy way to test it is like so:

 

[Ted]

Any possibility there is water in the fuel tank? If it started on a cold morning below zero, maybe ice blocking the fuel line? That would fit the "running out of fuel". Maybe someof the BS that Caiflornia requires tht isn't required in the rest of the USA?

This is my 4th winter here and only problem I have had was my 2 small cats burnt out and had codes over that. 0340 and another one which I dont remember but had something to do with the fuel sysyem.. It took me a little while to figure it out because it was throwing a code that said it was the fuel pump. Changed the fuel pump and still didnt help. Finally found what it was when I had to install a new rear main seal. On mine the section of exhaust had to come off that has the cats to remove the oil pan. Lucky I checked the thing when I had it off. I also changed the sensors on them. Put it pack together and code went away.

Sorry I can be of no help. Seems like mine runs better this time of year than it does in the summer. - double digits and it fires up like a champ.

 

[Chris Pierce]

Any possibility there is water in the fuel tank? If it started on a cold morning below zero, maybe ice blocking the fuel line? That would fit the "running out of fuel". Maybe someof the BS that Caiflornia requires tht isn't required in the rest of the USA?

This is my 4th winter here and only problem I have had was my 2 small cats burnt out and had codes over that. 0340 and another one which I dont remember but had something to do with the fuel sysyem.. It took me a little while to figure it out because it was throwing a code that said it was the fuel pump. Changed the fuel pump and still didnt help. Finally found what it was when I had to install a new rear main seal. On mine the section of exhaust had to come off that has the cats to remove the oil pan. Lucky I checked the thing when I had it off. I also changed the sensors on them. Put it pack together and code went away.

Sorry I can be of no help. Seems like mine runs better this time of year than it does in the summer. - double digits and it fires up like a champ.

Thanks for the reply Ted. I'm going to test the coil pack and see from there. Should I have to change my CPS sensor again? That'll be my 3rd one in 3 months


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[JP98]

@Chris Pierce take a look at the post Chris made about the P0306 code. Start eliminating those that would keep the Jeep from ever starting up. You know those can't be the case with it starting when it's above freezing. I'm with Ted about something in the fuel line causing the ECU to think it's lost fuel.