Hi Scotty, my 2019 toyota corolla S is showing a P0303 code. however i checked the plugs,ignition coil, fuel injectors, and even had a master tech at toyota checked it out. he found nothing wrong with the vehicle but every winter the check engine light goes on and sometimes the engine cranks but won't start. it starts after several turns of the key. what could be the problem?
Follow these steps when the issue surfaces & you should be able to pinpoint it - https://youtu.be/064Ilsz8Fzg
When you say master tech at Toyota, you mean the stealership kids?
Is the vehicle still under factory warranty?
Yes the speakership kids. The vehicle is no longer under warranty.
the vehicle starts at the first turn of the key now but intermittently, the check engine light comes on as a 3rd cylinder misfire.
it stays on for a while and then turns off only to return again. Leak tests were done but nothing was found. spark plugs changed. still no resolution.
it only seems to do this in the winter.
i replaced ignition coil but cylinder 3 is still misfiring p0303 code i think it is.
The car has 140,000 miles and has been kept up with maintenance. Is the engine wearing out already?
I highly doubt the engine is worn out, unless you rarely change your oil. You can rule that out easily by doing a wet & dry compression test.
Misfires can be caused by things other than the spark plugs & coils. https://www.engine-codes.com/p0303_toyota.html
Have you checked the wiring connectors of #3 coil & injector? How frequently do you change your engine oil?