2004 Volvo S40 cel is on, running rough

2004 VOLVO S40
105,000 MILES • 2.5L • 5 CYL • TURBO • 2WD • AUTOMATIC
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JASONSKITTY
  • MEMBER
  • 1 POST
after a quicker then normal acceleration at a stop light, the cel started flashing and car started running rough, i slowed down and cel remained on but stopped flashing. light is still on, car is still running rough and at about 45 mph the cel begins flashing again but goes off when i slow down. it is throwing code p0303...or p303...something like that. i know thats a miss in the 3rd cylinder and i am going to replace the plugs and all of that jazz....just wondering if you might have a suggestion of what else it could be in case this doesnt work.
Jul 9, 2015 at 5:40 PM
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JACOBANDNICKOLAS
  • ASE Certified Mechanic
  • 110,194 POSTS
  • ASE Certified Mechanic
Most likely, it is the plug. Other than that, it could be a plug wire, coil... Remove the plug and inspect its condition. Let me know what it looks like. Also, I recommend replacing all plugs at the same time and make sure to properly gap them.
Jul 9, 2015 at 8:11 PM
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