Q: I keep getting a cylinder 3 misfire code P0303. I have replaced the spark plugs and ignition coils and have had no luck.

asked by on December 21, 2016

I have had a cylinder 3 misfire code a few times and I have addressed the issue they way I was told to. Change plugs and coil but nothing seems to work. I have had a compression test done and all heads on the car are fine within 2 percent of one another. I don't smell any gas and the car does not shake. I don't believe I have any leaks as I check regularly. What else could be wrong?

My car has 66342 miles.
My car has an automatic transmission.

Hello There,

You may want to try checking things like mass air flow sensor, fuel pressure, injector connections/pulses, etc. Often times, when these components are not working properly or causing a lean fuel condition, this may cause a misfire due to the lack of enough fuel to properly ignite the air/fuel charge in the cylinder. You may also want to check for air or intake leaks as this can also contribute to a lean fuel condition that may potentially cause a misfire, although not quite as likely as the others mentioned.

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