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Make: Hyundai

Model: Accent

Engine: 1.6L

Year: 2008

Error codes: P0300,P0302

Knowledge level: I know little about cars

Help needed: Please help me find out what is going on and how to fix it.

  • 1
    Welcome to the site. What exactly happened? What is the issue? – Zaid Jul 11 '16 at 13:30
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P0300 is the trouble code for random/multiple misfires. P0302 is the trouble code for misfires in cylinder #2.

Common causes for misfires are :

  • Bad spark plugs. Remove them and inspect them. Replace them if necessary ($20 if you do it yourself). Tools needed: ratchet with various size sockets, spark plug socket, ratchet extension, spark plug gapper tool. First remove the plastic cover, then you will have the 4 ignition coils accessible. Twist them and yank them, they are really on there. Look deep inside the engine hole, that's the top of your spark plug. Use a spark plug socket and a ratchet extension and unscrew it, when it's loose, pull it out and compare it to this chart and measure the gap between the curvy part and the thin grain of rice part. I believe the gap needed for your case is 0.045". If the gap is too big, gently tap the curvy part against something hard. If it's too small, use the gapper tool to gently pry it open. We are talking fractions of an inch, so just apply some mild force, less than opening a can of pop, and measure. New spark plugs need to have their gap checked the same way.
  • Bad ignition coils If changing the spark plugs doesn't prevent your problem from reappearing, your next likely culprit are the ignition coils. They are about $20 each, replace the entire set. Only remove them 1 at a time, because the order they are connected in matters. Remove one, replace it. Then move to the next one.
  • Bad injector There isn't an easy way to diagnose a bad injector and replacing them involved releaving fuel pressure, that may be too dangerous for a novice.
  • An easy way to check an injector is to put an amp clamp around the power wire. This allows you to view pintle movement in the waveform. – Ben Jul 11 '16 at 19:06
  • I'd add the cables to the spark plugs, too. If the insulation is porous, this could lead to misfires, especially in wet weather conditions. – sweber Jul 11 '16 at 19:24
  • Im getting the same codes I've replaced the plugs/wire's/water pump/timing belt/ its driving me craze and i am not a a car person hoping the new coil i orderd will fix it – Nathan Jan 14 at 1:34
  • @Nathan Water pump and timing belt have nothing to do with a misfire. Did your car need these for a separate reason? – tlhIngan Jan 17 at 8:08

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