Home › Forums › Stay Dirty Lounge › Service and Repair Questions Answered Here › 2003 corolla code p0304 "misfire #4 cyl" › Reply To: 2003 corolla code p0304 "misfire #4 cyl" February 16, 2020 at 9:25 pm #915286 Richard KirshyParticipant Suggest doing a leak down test to attempt to narrow the possible cause.