I was wondering if anyone here can figure out the way my '03 throws the p0300 code. The usual way is just by driving @ 75mph and you throw a code. With my situation it is different. In the morning I would go to work and drive between 70-80 mph and throw no code. Same thing on the way home. But if I leave my house and stop the engine to get coffee or gas, I would get the p0300 codes like crazy. The same thing happens on my way home if I stop somewhere and restart the car, I would get the code like every 5 min. Curious, why is it that if I start my car, from not being used for @ 8hrs. and start it once and drive, I get no p0300 code? But if I start it and restart it, I get the code. Anyone knows?

 

Not sure if you've done it yet, but first thing you should do is to go to your local dealer and get your PCM reflashed. The newest program for your car addresses the P0300 random misfire problem. Spark plugs can also cause a random misfire, but unlikely if you've got low miles. Injectors are also a problem, especially if any additives have been added to your gas tank. Sticking injectors will cause the code to set at idle with a warm engine, and not at high speeds, as is your situation. This would be my guess as the cause of the code. If you can get your car scanned, PM me the freeze frame data and I can see if I can help you more. First, the PCM reflash.