2006 intermittent crankshaft position sensor and other random

[TerryD]

A few weeks ago the wife and I were out riding during some mild flooding and it popped a Crankshaft Position Sensor code and Random Multiple Cylinder Missfire code. Limped it home with a flashing CEL and inability to revv over 2100rpm.

Pulled the Crankshaft Position Sensor and the end was cracked and it had been wiping on the tone ring. Figured I had the issue licked after swapping in a new NTK/NGK sensor from my spares box and clearing the code.

Fast forward to today, driving around town after washing the Jeep and it stumbled and threw the code again with a flashing CEL. Limped it home, inspected the Crankshaft Position Sensor and harness for any damage. No obvious issues with anything. Picked up some new loom and started replacing the old/damaged/missing wire loom up the harness. Added a touch of dielectric grease to the seal on the Crankshaft Position Sensor like I usually do and went for a test drive.

All was good for several miles at varied speeds then it just died. Restarted after a short crank, flashing CEL and Crankshaft Position Sensor/Missfire codes. Shut it off, cleared the code and drove hone without issue. Went out later and drove around town without issue.

I looked around the harness anywhere loom is missing (will be working on replacing it as I have the time) and I didn't see any bad spots. I even started the Jeep and shook and wiggled the harness from the Crankshaft Position Sensor back to the ECM to see if there was an area that would cause a stumble and couldn't find anything.

Any ideas of other issues to check?

3/11/25 Update:

You’re going to call me crazy, but… I have seen on Jeep specifically where the cam sensor gets hot and the internal transistor fails. When it does, while watching the cam sensor signal wire on an oscilloscope, it goes from a clean 5 to 0 volt square wave, to fuzzy nonsense. This kills the engine. The computer is too stupid to interpret this nonsense as,… nonsense, and instead makes the determination that “the cam is still producing a signal, but the crank isn’t” and therefore sets an incorrect crank sensor DTC. Newer vehicles have an “Implausible Cam Signal” DTC the PCM can set that fixes this issue. Ours, do not.

To add a log to this fire, the fact that you said you couldn’t get it over 2100 rpm, tells me that the PCM is, in fact, seeing a good crank signal when all this is happening. Otherwise, you’d have no indicated RPM on the gauge.

You could experiment with the oscilloscope if you wanted. I’d be happy to walk you through the process. But my guess is that’s not a tool in your arsenal, and cam sensors are a cheap guess.

I have not had the issue again but decided to swap in my spare Camshaft Position Sensor just in case and also because the mounting boss on the (what I assume is original Mopar) Camshaft Position Sensor was broken and glued back together.

First start after the swap was a hot start since I did it right after I got home from work. It started much faster than it has been starting which I'm going to take as a good indication that the Camshaft Position Sensor was indeed failing.

I'll report back. Thanks

3/23/25 Update:
The oldest and I went out on a "get away from everyone else" trip today. About 20min from the house, on our way back, the Jeep threw a P0344 "Camshaft Position Sensor A Intermittent"

This is the sensor I just swapped in recently so I was flabbergasted. I couldn't get my OBD reader to reset the code and couldn't run more than about 2400 RPM (up from the 2100 when I was getting crankshaft position sensor codes) but managed to limp it home.

I lost my temper and just swapped the new Crown OPDA in, hoping for an insane amount of luck. Fired it up and it threw the P0016 Cam Crank relation code. Moved the OPDA a little and no change.

I desperation, I swapped back in the cam sensor from the old OPDA, pulled the battery terminal. No change. I turned the OPDA clockwise just a bit, unhooked the battery and hooked it back up, then tried it again and viola, no codes.

I took it on a long test drive and had no issues.

There was a lot of metal shavings in the old OPDA. My working theory is that they were causing issues with the pickup but that's a guess. No other issues to be seen.

FWIW my transmission has been shifting out of 1st funny for several days. After pulling the battery terminal it's shifting normally again.

 

[rasband]

This sounds an awful lot like the PCM, aside from the first sensor having contact. Here's two of my threads on this. I'd call @Wranglerfix to talk about it or read the numerous threads here.

Thread 'Intermittent Stalling Help'

Sep 7, 2019

Leading up to this I had no obvious signs, and wheeled last weekend without issue (thankfully).

I am getting intermittent stalling that I just can't figure out and haven't gotten a consistent CEL (I believe one was a red herring - a misdirection, which we will get to in a minute).

So far (with tests between each change that included parts)

* First Stall
* P0457 - replaced my OEM locking gas cap with an OEM non locking
* More stalls
* Replaced the Crank and Cam sensors (both were replaced last fall with the same issue... I had them in the bin in-case the others weren't MOPAR (these were...

• rasband
• p0355 u0155
• Replies: 60
• Forum: TJ General Discussion

Thread 'SOLVED: Engine cutting out with sporadic speedometer behavior and fine after a break'

Sep 17, 2018

I just purchased a 2006 Rubicon Unlimited in impeccable shape by all accounts: clean engine, low miles, good service history, no rust, and lived its life in the dry portions of the western US (mid Texas to Colorado).

The Car:

• 2006 Rubicon Unlimited
  
• 6 Speed Manual
• 4.0L
• 50,000 miles (definitely someone's extra car)
• Stock (no lift, no major mods beyond a winch, some fog lights, upgraded battery)
  
• All the standard rubi unlimited stuff
• Nearly brand new tires, the stock spec Goodyear Wranglers (~30.5")

I knew what I was looking for and when it popped up I...

• rasband
• 4.0 lj manual tj
• Replies: 31
• Forum: TJ General Discussion

 

[ItchyDong]

You’re going to call me crazy, but… I have seen on Jeep specifically where the cam sensor gets hot and the internal transistor fails. When it does, while watching the cam sensor signal wire on an oscilloscope, it goes from a clean 5 to 0 volt square wave, to fuzzy nonsense. This kills the engine. The computer is too stupid to interpret this nonsense as,… nonsense, and instead makes the determination that “the cam is still producing a signal, but the crank isn’t” and therefore sets an incorrect crank sensor DTC. Newer vehicles have an “Implausible Cam Signal” DTC the PCM can set that fixes this issue. Ours, do not.

To add a log to this fire, the fact that you said you couldn’t get it over 2100 rpm, tells me that the PCM is, in fact, seeing a good crank signal when all this is happening. Otherwise, you’d have no indicated RPM on the gauge.

You could experiment with the oscilloscope if you wanted. I’d be happy to walk you through the process. But my guess is that’s not a tool in your arsenal, and cam sensors are a cheap guess.

 

[TerryD]

You’re going to call me crazy, but… I have seen on Jeep specifically where the cam sensor gets hot and the internal transistor fails. When it does, while watching the cam sensor signal wire on an oscilloscope, it goes from a clean 5 to 0 volt square wave, to fuzzy nonsense. This kills the engine. The computer is too stupid to interpret this nonsense as,… nonsense, and instead makes the determination that “the cam is still producing a signal, but the crank isn’t” and therefore sets an incorrect crank sensor DTC. Newer vehicles have an “Implausible Cam Signal” DTC the PCM can set that fixes this issue. Ours, do not.

To add a log to this fire, the fact that you said you couldn’t get it over 2100 rpm, tells me that the PCM is, in fact, seeing a good crank signal when all this is happening. Otherwise, you’d have no indicated RPM on the gauge.

You could experiment with the oscilloscope if you wanted. I’d be happy to walk you through the process. But my guess is that’s not a tool in your arsenal, and cam sensors are a cheap guess.

All the codes have been for Crankshaft Position Sensor, sorry. I shouldn't have used the abbreviation in my post. Thanks for the input though.

 

[TheBoogieman]

I couldn't even limp home when mine went bad. I replaced the camshaft and crankshaft sensors just to be sure. Fixed my issue of getting stranded.

 

[ItchyDong]

All the codes have been for Crankshaft Position Sensor, sorry. I shouldn't have used the abbreviation in my post. Thanks for the input though.

If you read what I posted, that’s exactly what I’m saying. The cam sensor fails, but the PCM interprets it as a bad crankshaft sensor.

 

[JKP]

You can disconnect the cam sensor and drive it on just the crank sensor to see if that fixes it. It will be a long crank to start.

And, you can disconnect the crank sensor and run it on just the cam sensor. Same long crank to start.

 

[TerryD]

If you read what I posted, that’s exactly what I’m saying. The cam sensor fails, but the PCM interprets it as a bad crankshaft sensor.

I read it but it didn't sink in. I defaulted to you thinking I meant the cam sensor since my post used mostly "cps".

I will check that out. I do have a spare Standard cam sensor in my parts box as well.

 

[TerryD]

You’re going to call me crazy, but… I have seen on Jeep specifically where the cam sensor gets hot and the internal transistor fails. When it does, while watching the cam sensor signal wire on an oscilloscope, it goes from a clean 5 to 0 volt square wave, to fuzzy nonsense. This kills the engine. The computer is too stupid to interpret this nonsense as,… nonsense, and instead makes the determination that “the cam is still producing a signal, but the crank isn’t” and therefore sets an incorrect crank sensor DTC. Newer vehicles have an “Implausible Cam Signal” DTC the PCM can set that fixes this issue. Ours, do not.

To add a log to this fire, the fact that you said you couldn’t get it over 2100 rpm, tells me that the PCM is, in fact, seeing a good crank signal when all this is happening. Otherwise, you’d have no indicated RPM on the gauge.

You could experiment with the oscilloscope if you wanted. I’d be happy to walk you through the process. But my guess is that’s not a tool in your arsenal, and cam sensors are a cheap guess.

I have not had the issue again but decided to swap in my spare Camshaft Position Sensor just in case and also because the mounting boss on the (what I assume is original Mopar) Camshaft Position Sensor was broken and glued back together. First start after the swap was a hot start since I did it right after I got home from work. It started much faster than it has been starting which I'm going to take as a good indication that the Camshaft Position Sensor was indeed failing.

I'll report back. Thanks

*added to first post as a possible fix*

 

[TerryD]

Several days have passed. I've put over 250 miles on it, including one 5hr round trip and so far so good.

It did have an issue at stop lights later in the day. It would idle very rough and bank 1 STFT would go way negative. Like -15% or so. I'm wondering if I have an injector that's not closing completely causing that issue. If it starts happening more frequently, I'll swap the front and rear sets to see if it follows the injectors or if it's possibly a driver issue.

The OPDA arrived but I haven't had opportunity to install it yet.

 

[ItchyDong]

Several days have passed. I've put over 250 miles on it, including one 5hr round trip and so far so good.

It did have an issue at stop lights later in the day. It would idle very rough and bank 1 STFT would go way negative. Like -15% or so. I'm wondering if I have an injector that's not closing completely causing that issue. If it starts happening more frequently, I'll swap the front and rear sets to see if it follows the injectors or if it's possibly a driver issue.

The OPDA arrived but I haven't had opportunity to install it yet.

Good deal. Sounds like you’ve got it whooped. You’re on the right track with the negative trims. Did it ever set a misfire code when it was stumbling? If not, it’s more than likely an injector.

 

[TerryD]

Good deal. Sounds like you’ve got it whooped. You’re on the right track with the negative trims. Did it ever set a misfire code when it was stumbling? If not, it’s more than likely an injector.

No missfire codes. Just the rough idle. Cleared up once I took off.

Gave it a double dose of seafoam to see if that'll help any.

Is there a preferred place to buy injectors for these?

 

[ItchyDong]

No missfire codes. Just the rough idle. Cleared up once I took off.

Gave it a double dose of seafoam to see if that'll help any.

Is there a preferred place to buy injectors for these?

I’m not certain. I try to stick with mopar if at all possible. I got six from rock auto a few years ago but who knows.

 

[TerryD]

Today I found one of my injector bodies cracked so I ordered a full set of injectors from Precision Auto Injectors. $300 for a full set of rebuilt Bosch 4 hole injectors with a lifetime warranty and all the seals.

I also have a Crown OPDA sitting on the bench ready to go in when I get the time.

 

[TerryD]

I'll update the first post later.

The oldest and I went out on a "get away from everyone else" trip today. About 20min from the house, on our way back, the Jeep threw a P0344 "Camshaft Position Sensor A Intermittent"

This is the sensor I just swapped in recently so I was flabbergasted. I couldn't get my OBD reader to reset the code and couldn't run more than about 2400 RPM (up from the 2100 when I was getting crankshaft position sensor codes) but managed to limp it home.

I lost my temper and just swapped the new Crown OPDA in, hoping for an insane amount of luck. Fired it up and it threw the P0016 Cam Crank relation code. Moved the OPDA a little and no change.

I desperation, I swapped back in the cam sensor from the old OPDA, pulled the battery terminal. No change. I turned the OPDA clockwise just a bit, unhooked the battery and hooked it back up, then tried it again and viola, no codes.

I took it on a long test drive and had no issues.

There was a lot of metal shavings in the old OPDA. My working theory is that they were causing issues with the pickup but that's a guess. No other issues to be seen.

FWIW my transmission has been shifting out of 1st funny for several days. After pulling the battery terminal it's shifting normally again.

 

[TerryD]

Small bit of what was in the bottom of the OPDA under the encoder wheel on the end of my little magnet.

 

[TerryD]

So far so good today. *shrug*

 

[TerryD]

Today I'm positive it's a moisture issue. I've put several hundred miles on the Jeep since my last issue and it's run flawlessly.

Today I washed the Jeep then we pulled off the top and went for ice cream. About 10 minutes in it started missing and threw the Crankshaft Position Sensor Circuit A code again.

Drove it on to the ice cream place, had our little treat and when we restarted it, it still had a code but ran great on the way home and since. I have not been able to clear the code and haven't pulled the battery cable to reset it but that's not relevant, at least I don't believe it is.

Next day I get time, I'm going to dig in to that section of harness and start looking for damage.

 

[DougyintheBushies]

Today I'm positive it's a moisture issue. I've put several hundred miles on the Jeep since my last issue and it's run flawlessly.

Today I washed the Jeep then we pulled off the top and went for ice cream. About 10 minutes in it started missing and threw the Crankshaft Position Sensor Circuit A code again.

Drove it on to the ice cream place, had our little treat and when we restarted it, it still had a code but ran great on the way home and since. I have not been able to clear the code and haven't pulled the battery cable to reset it but that's not relevant, at least I don't believe it is.

Next day I get time, I'm going to dig in to that section of harness and start looking for damage.

Any news on this?

 

[TerryD]

No real change for a while now. The one fluke during the really heavy rain I encountered around Raleigh but a key off-key on restart got it running fine and it cleared and hasn't reset yet.