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Chrysler Repair/2007 Aspen misfire - P0300


Hello.  My check engine light has been on for several months. It is throwing a P0300 (among others). The problem is on startup, the vehicle really struggles like it is not getting enough gas.  I can put it in neutral, press on the gas and that helps, it only lasts for about 30 seconds then runs fine.  It doesn't matter if the vehicle has been sitting overnight or was shut off 30 minutes prior.

I have replaced the EGR valve, the PCM, cat on bank 1, spark plugs, had two fuel injection cleanings, PSIM(?) valve and an oxygen sensor (I think the front).  There have been other things done, but unfortunately I have misplaced the paperwork. It actually runs worse since the cat was replaced.  Any ideas of what to do next?  Thank you!

Hi Jonnie,
The causes for the 0300 (missing) are many and I can list them. But tell me what are all the current fault codes as one of those may be more specific. The idle air passageway or the idle control "motor" may be gummed up. You could try cleaning the throat of the throttle body, both sides of the butterfly valve plate, and the side air passageway using some solvent. If that doesn't work then you could remove the screws on the side of the throttle body that retain the pintel which moves back and forth and constitutes the "motor" of the idle control and clean off that and its passage.

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Roland Finston


Get a Free Fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

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