Troubleshooting a PO300 and PO306 CEL on a 2004 Rubicon

Accelerometer

Accelerometer

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Apr 22, 2023
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Location
San Mateo CA
I recently purchased a 2004 Rubicon 5MT with 92,000 miles on it about a month ago and everything has been smooth sailing for the most part. The other day while driving home from an OHV park I had an intermittent CEL flash on the dash and then go away. When I got home I pulled a P0300 and P0306 from my OBD tool.

Additional Context
  • For the most part the engine has been running smooth over the last month
  • While the CEL was flashing I was cruising around 70 mph on the highway and felt no noticeable change in engine performance
  • On two separate occasions over the last month the Jeep had a hard time cranking over which required me to crank it over again to get it started
  • The Jeep on two other occasions ran really rough at startup and exhibited some ticking which went away once warmed up
  • The previous owner mentioned replacing a Camshaft Sensor recently so I'm probably going to rule that out
Given the misfires seem to be across multiple cylinders im thinking the problem is most likely upstream from the spark plugs. From research on this site and other sources the crankshaft position sensor seems to be a good candidate as the source of this problem. So I am planning on replacing that first and I'll also replace the spark plugs given that they are probably original and need to be replaced anyways. Any feedback on this approach or other areas you think I should be paying attention to? Many thanks
 
OCJeepGirl said:
Any update? I seem to be having similar issue.
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Hi sorry, life is getting to me and this isn't my primary vehicle. The CEL hasnt come on since then and I will most likely be replacing the spark plugs this weekend. Ill see if that does the trick because im dreading trying to pull the Crankshaft sensor.
 
Last edited:
Accelerometer said:
Sorry i keep mixing up Camshaft and Crankshaft when I type fast, the Crankshaft Position Sensor is difficult to get to
Click to expand...

Difficult is relative, but it really isn't very hard at all. But yes, slightly harder than the cam sensor. Good luck with your tests.
 
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