2003 Chrysler PT Cruiser P0300 code

2003 CHRYSLER PT CRUISER
73,000 MILES • 4 CYL • FWD • AUTOMATIC
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PTCRUISER
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Hi,

My 2003 PT Cruiser GT has been haunting me with a misfire code for the past 4 months and it's time for it to go! The symptoms I receive are as follows; very hard to get started, idles very rough, and sometimes the engine dies when there is a large load on the engine (lights, radio, heater on while braking). Funny thing is, when the engine warms up, it starts right away, and while driving it seems to run wonderfully. I have changed the spark plugs and wires. The wires are the correct gauge and the plugs are gapped to the right size. I don't want to go to a shop since I am mechanically inclined, and I am trying my best to avoid a pricey troubleshooting process. Especially with today's economy! I would appreciate any advice you can offer guys!

Thanks,

-Nate
Feb 24, 2009 at 5:41 PM
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2CARPRO JACK
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So it has only given P0300? You may have a bad coil. Usually misfires under load are ignition related, injectors tend to miss at idle then go away when rpms are attained.A weak/bad coil can cause cold starting problems.Also check the fuel pressure regulator on the fuel rail with a vacuum line to intake, if any fuel is in the vacuum line replace the regualtor
Feb 25, 2009 at 7:51 AM
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PTCRUISER
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I am sorry, I had just learned if I turn the key from off to run back and fourth 3 times then I get a read out of all codes in the tach display. I also have a P0522 and a barometric pressure low code. But they come and go, the P0300 is there all the time. Thanks for the advise thus far. I will try out what you recomended and get back to you.
Feb 25, 2009 at 3:39 PM
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2CARPRO JACK
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The P0522 is for a low oil pressure reading.Be sure it is full, may have a bad sensor.Do you know th eexact # for the Baro code, that can harm performance as well
Feb 25, 2009 at 4:17 PM
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PTCRUISER
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the exact code is P0129
Feb 25, 2009 at 7:55 PM
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PTCRUISER
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Hey I replaced the ignition coil and I no longer have a hard time starting the car. Thank you!! But I still have a P0300 - random misfire code. I am exhausted on ideas.
Feb 26, 2009 at 5:39 PM
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ZACKMAN
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https://www.2carpros.com/forum/automotive_pictures/55316_03gtcruisermil_1.jpg

Replacing the coil would have been the fix that you need for the P0300. But the CEL has to be either physically reset via an OBD-II scan tool or 3 good trips without any problems seen by the PCM. I would suggest that you bring the vehicle to your local Autozone, and they can read and then erase/reset the computer. Please be sure though that you only receive P0300 from their scanner prior to erasing. If they find any other DTCs or codes, please report back with the code numbers.
Feb 27, 2009 at 1:00 AM
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PTCRUISER
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Well. The problem still seems to be present. The car has the same symptoms; rough idle, hard to start when cold, and sputters under load on low rpm's. I am going to change the spark plugs to see if they are fouled. After that I am out of ideas! HELP!!
Mar 5, 2009 at 6:12 AM
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2CARPRO JACK
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Did you get the codes cleared properly so that we can see what comes back?
Mar 16, 2009 at 8:04 AM
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PTCRUISER2004
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Hi i had the same problem with my 2004 pt cruiser. Changed spark plugs fixed any leaks i had changed also both oxygen sensors and also went to dealers to have my powertrain module downloaded with new software. This was a fix for me. My pt Cruiser has 243,000km on it sounds like new. Idle is smooth and no more misfire. Hope this helps anyone whos having problems p0300 is a code usally somethings wrong with sparkplugs/wires and or you need to get your powertrain updated with new software.
Apr 28, 2016 at 6:09 PM